Management of breast diseases 2nd ed

Ismail Jatoi
Achim Rody
Editors

Management of
Breast Diseases
Second Edition

123


Management of Breast Diseases


Ismail Jatoi Achim Rody
•

Editors

Management of Breast
Diseases
Second Edition

123


Editors
Ismail Jatoi
Department of Surgery
University of Texas Health Science Center
San Antonio, TX

USA

ISBN 978-3-319-46354-4
DOI 10.1007/978-3-319-46356-8

Achim Rody
Obstetrics and Gynecology
University Medical Center
Schleswig-Holstein
Lübeck
Germany

ISBN 978-3-319-46356-8

(eBook)

Library of Congress Control Number: 2016951967
1st edition: © Springer-Verlag Berlin Heidelberg 2010
2nd edition: © Springer International Publishing Switzerland 2016
This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is
concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction
on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic
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The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not
imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and
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The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed
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Preface

In 2002, Lippincott published the Manual of Breast Diseases, edited by Prof. Ismail Jatoi. That
book was expanded and a larger text entitled Management of Breast Diseases was published
by Springer in 2010, edited by Prof. Jatoi and Prof. Manfred Kaufmann of the
Goethe-University of Frankfurt. Professor Kaufmann subsequently retired, and the current text
is the second edition of the Springer text, with Prof. Achim Rody of the University Hospital
Schleswig-Holstein in Lübeck, Germany now serving as co-editor. Many of the chapters have
been extensively revised and numerous other authors have been added to the second edition of
this text. We hope that this updated text will continue to serve as a useful guide to the wide
spectrum of clinicians who treat benign and malignant diseases of the breast: surgeons,
gynecologists, medical oncologists, radiation oncologists, internists, and general practitioners.
Today, the management of breast diseases, and particularly breast cancer, is predicated
upon the results of large randomized prospective trials. The authors of the various chapters in
this text have highlighted the major trials that have contributed to our improved understanding
and treatment of breast diseases. Many of these trials have, in particular, revolutionized the
treatment of breast cancer. Indeed, there has been a very rapid decline in breast cancer
mortality throughout the industrialized world since 1990, due largely to the implementation
of the results of landmark randomized trials. For this progress to continue, we will need to
design innovative trials in the future, and recruit large numbers of women into those trials. We
should always be grateful to the thousands of women throughout the world who have participated in clinical trials, and thereby enabled progress in the treatment of breast cancer.
We are deeply indebted to all the investigators who have contributed chapters to this text.
They have diverse interests, but all share the common goal of reducing the burden of breast
diseases. We would also like to thank the editorial staff of the Springer publishing company

for their continued assistance with updating this text. In particular, we are most grateful to
Portia Levasseur of the Springer publishing company. Without Portia’s persistence and diligence, this second edition would not have been possible. We hope that clinicians will continue
to find this text to be an informative guide to the management of breast diseases.
San Antonio, USA
Lübeck, Germany

Ismail Jatoi
Achim Rody

v


Contents

1

Anatomy and Physiology of the Breast . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Martha C. Johnson and Mary L. Cutler

1

2

Congenital and Developmental Abnormalities of the Breast . . . . . . . . . . . . .
Kristin Baumann and Telja Pursche

41

3

Nipple Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jill R. Dietz

57

4

Mastalgia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Amit Goyal and Robert E. Mansel

73

5

Management of Common Lactation and Breastfeeding Problems . . . . . . . . .
Lisa H. Amir and Verity H. Livingstone

81

6

Evaluation of a Breast Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Alastair M. Thompson and Andrew Evans

7

Breast Cancer Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Alicia Brunßen, Joachim Hübner, Alexander Katalinic, Maria R. Noftz,
and Annika Waldmann

8

Breast Cancer Screening. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Ismail Jatoi

9

Breast Imaging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Anne C. Hoyt and Irene Tsai

10 Premalignant and Malignant Breast Pathology . . . . . . . . . . . . . . . . . . . . . . 179
Hans-Peter Sinn
11 Breast Cancer Molecular Testing for Prognosis and Prediction. . . . . . . . . . . 195
Nadia Harbeck
12 Molecular Classification of Breast Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Maria Vidal, Laia Paré, and Aleix Prat
13 Ductal Carcinoma In Situ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Ian H. Kunkler
14 Surgical Considerations in the Management of Primary Invasive
Breast Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Carissia Calvo and Ismail Jatoi
15 Management of the Axilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
John R. Benson and Vassilis Pitsinis
16 Breast Reconstructive Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Yash J. Avashia, Amir Tahernia, Detlev Erdmann, and Michael R. Zenn

vii


viii

17 The Role of Radiotherapy in Breast Cancer Management . . . . . . . . . . . . . . 291
Mutlay Sayan and Ruth Heimann
18 Adjuvant Systemic Treatment for Breast Cancer: An Overview . . . . . . . . . . 311
Rachel Nirsimloo and David A. Cameron
19 Endocrine Therapy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
Olivia Pagani and Rosaria Condorelli
20 Systemic Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
Frederik Marmé
21 HER2-Targeted Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
Phuong Dinh and Martine J. Piccart
22 Inflammatory and Locally Advanced Breast Cancer. . . . . . . . . . . . . . . . . . . 411
Tamer M. Fouad, Gabriel N. Hortobagyi, and Naoto T. Ueno
23 Neoadjuvant Systemic Treatment (NST) . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
Cornelia Liedtke and Achim Rody
24 Metastatic Breast Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Berta Sousa, Joana M. Ribeiro, Domen Ribnikar, and Fátima Cardoso
25 Estrogen and Breast Cancer in Postmenopausal Women:
A Critical Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475
Joseph Ragaz and Shayan Shakeraneh
26 Estrogen and Cardiac Events with all-cause Mortality.
A Critical Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Joseph Ragaz and Shayan Shakeraneh
27 Breast Diseases in Males . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Darryl Schuitevoerder and John T. Vetto
28 Breast Cancer in the Older Adult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
Emily J. Guerard, Madhuri V. Vithala, and Hyman B. Muss
29 Breast Cancer in Younger Women . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529
Manuela Rabaglio and Monica Castiglione
30 Psychological Support for the Breast Cancer Patient . . . . . . . . . . . . . . . . . . 565

Donna B. Greenberg
31 Management of the Patient with a Genetic Predisposition
for Breast Cancer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575
Sarah Colonna and Amanda Gammon
32 Chemoprevention of Breast Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593
Jack Cuzick
33 Design, Implementation, and Interpretation of Clinical Trials . . . . . . . . . . . . 601
Carol K. Redmond and Jong-Hyeon Jeong
34 Structure of Breast Centers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637
David P. Winchester
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 649

Contents


Contributors

Lisa H. Amir Judith Lumley Centre, La Trobe University, Melbourne, VIC, Australia;
Breastfeeding service, Royal Women’s Hospital, Melbourne, Australia
Yash J. Avashia Surgery, Duke University Medical Center, Durham, NC, USA
Kristin Baumann Clinic for Gynaecology and Obstetrics, University Medical Centre
Schleswig-Holstein Campus Lübeck, Lübeck, Schleswig-Holstein, Germany
John R. Benson Cambridge Breast Unit, Addenbrooke’s Hospital, Cambridge University
Hospitals NHS Trust, Cambridge, UK
Alicia Brunßen Department of Surgery, University of Texas Health Science Center at San
Antonio, San Antonio, TX, USA
Carissia Calvo Department of Surgery, University of Texas Health Science Center, San
Antonio, TX, USA
David A. Cameron Edinburgh Cancer Research Centre, Western General Hospital,
University of Edinburgh, Edinburgh, UK

Fátima Cardoso Breast Unit, Champalimaud Clinical Center, Lisbon, Portugal
Monica Castiglione Coordinating Center, International Breast Cancer Study Group
(IBCSG), Berne, Switzerland
Sarah Colonna Oncology, Huntsman Cancer Institute, Salt Lake City, UT, USA
Rosaria Condorelli Department of Medical Oncology, Institute of Oncology of Southern
Switzerland, Bellinzona, Switzerland
Mary L. Cutler Department of Pathology, Uniformed Services University, Bethesda, MD,
USA
Jack Cuzick Wolfson Institute of Preventive Medicine, Queen Mary University of London,
Centre for Cancer Prevention, London, UK
Jill R. Dietz Surgery, University Hospitals Seidman Cancer Center, Bentleyville, OH, USA
Phuong Dinh Westmead Hospital, Westmead, NSW, Australia
Detlev Erdmann Surgery, Duke University Medical Center, Durham, NC, USA
Andrew Evans Division of Imaging and Technology, University of Dundee, Dundee,
Scotland, UK
Tamer M. Fouad Department of Breast Medical Oncology, The University of Texas MD
Anderson Cancer Center, Houston, TX, USA

ix


x

Amanda Gammon High Risk Cancer Research, Huntsman Cancer Institute, Salt Lake City,
UT, USA
Amit Goyal Royal Derby Hospital, Derby, UK
Donna B. Greenberg Department of Psychiatry, Harvard Medical School, Massachusetts
General Hospital, MGH Cancer Center, Boston, MA, USA
Emily J. Guerard Medicine, Division of Hematology Oncology, University of North
Carolina, Chapel Hill, NC, USA

Nadia Harbeck Breast Center, University of Munich, Munich, Germany
Ruth Heimann Department of Radiation Oncology, University of Vermont Medical Center,
Burlington, VT, USA
Gabriel N. Hortobagyi Department of Breast Medical Oncology, The University of Texas MD
Anderson Cancer Center, Houston, TX, USA
Anne C. Hoyt Department of Radiological Sciences, UCLA, Los Angeles, CA, USA
Joachim Hübner Institute for Social Medicine and Epidemiology, University of Luebeck,
Luebeck, Schleswig-Holstein, Germany
Ismail Jatoi Division of Surgical Oncology and Endocrine Surgery, University of Texas
Health Science Center, San Antonio, TX, USA
Jong-Hyeon Jeong Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA,
USA
Martha C. Johnson Department of Anatomy, Physiology and Genetics, Uniformed Services
University, Bethesda, MD, USA
Alexander Katalinic Institute for Social Medicine and Epidemiology, University of
Luebeck, Luebeck, Schleswig-Holstein, Germany
Ian H. Kunkler Institute of Genetics and Molecular Medicine (IGMM), University of
Edinburgh, Edinburgh, Scotland, UK
Cornelia Liedtke Department of Obstetrics and Gynecology, University Hospital
Schleswig-Holstein/Campus Lübeck, Luebeck, Schleswig-Holstein, Germany
Verity H. Livingstone Department of Family Practice, The Vancouver Breastfeeding Centre,
University of British Columbia, Vancouver, BC, Canada
Robert E. Mansel Cardiff University, Monmouth, UK
Frederik Marmé Department of Gynecologic Oncology, National Center of Tumor Diseases, Heidelberg University Hospital, Heidelberg, Germany
Hyman B. Muss Medicine, Division of Hematology Oncology, University of North Carolina, Chapel Hill, NC, USA
Rachel Nirsimloo Edinburgh Cancer Centre, NHS LOTHIAN, Edinburgh, UK
Maria R. Noftz Institute for Social Medicine and Epidemiology, University of Luebeck,
Luebeck, Schleswig-Holstein, Germany
Olivia Pagani Institute of Oncology and Breast Unit of Southern Switzerland, Ospedale San
Giovanni, Bellinzona, Ticino, Switzerland

Laia Paré Translational Genomics and Targeted Therapeutics in Solid Tumors Lab, August
Pi I Sunyer Biomedical Research Institute (IDIBAPS), Barcelon, Spain

Contributors


Contributors

xi

Martine J. Piccart Medicine Department, Institut Jules Bordet, Bruxelles, Belgium
Vassilis Pitsinis Breast Unit, Ninewells Hospital and Medical School, NHS Tayside, Dundee,
UK
Aleix Prat Medical Oncology, Hospital Clinic of Barcelona, Barcelona, Spain
Telja Pursche Clinic for Gynaecology and Obstetrics, University Medical Centre
Schleswig-Holstein Campus Lübeck, Lübeck, Schleswig-Holstein, Germany
Manuela Rabaglio Department of Medical Oncology, University Hospital/Inselspital and
IBCSG Coordinating Center, Berne, Switzerland
Joseph Ragaz School of Population and Public Health, University of British Columbia,
North Vancouver, BC, Canada
Carol K. Redmond Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA,
USA
Joana M. Ribeiro Breast Unit, Champalimaud Clinical Center, Lisbon, Portugal
Domen Ribnikar Medical Oncology Department, Institute of Oncology Ljubljana, Ljubljana, Slovenia
Achim Rody Department of Obstetrics and Gynecology, University
Schleswig-Holstein/Campus Lübeck, Luebeck, Schleswig-Holstein, Germany

Hospital

Mutlay Sayan Department of Radiation Oncology, University of Vermont Medical Center,

Burlington, VT, USA
Darryl Schuitevoerder Department of Surgery, Oregon Health & Science University,
Portland, OR, USA
Shayan Shakeraneh Infection Prevention and Control, Providence Health Care, Vancouver,
BC, Canada; School of Population and Public Health, University of British Columbia,
Vancouver, BC, Canada
Hans-Peter Sinn Department of Pathology, University of Heidelberg, Heidelberg,
Baden-Württemberg, Germany
Berta Sousa Breast Unit, Champalimaud Clinical Center, Lisbon, Portugal
Amir Tahernia Plastic and Reconstructive Surgery, Beverly Hills, CA, USA
Alastair M. Thompson Department of Breast Surgical Oncology, University of Texas MD
Anderson Cancer Center, Houston, TX, USA
Irene Tsai Department of Radiological Sciences, UCLA, Los Angeles, CA, USA
Naoto T. Ueno Department of Breast Medical Oncology, The University of Texas MD
Anderson Cancer Center, Houston, TX, USA
John T. Vetto Department of Surgery, Division of Surgical Oncology, Oregon Health &
Science University, Portland, OR, USA
Maria Vidal Medical Oncology, Hospital Clinic of Barcelona, Barcelona, Spain
Madhuri V. Vithala Duke University, Durham Veteran Affairs, Durham, NC, USA
Annika Waldmann Institute for Social Medicine and Epidemiology, University of Luebeck,
Luebeck, Schleswig-Holstein, Germany
David P. Winchester American College of Surgeons, Chicago, IL, USA
Michael R. Zenn Surgery, Duke University Medical Center, Durham, NC, USA


1

Anatomy and Physiology of the Breast
Martha C. Johnson and Mary L. Cutler

Abbreviations

BCL-2
BRCA1
BM
BrdU
CD
CSF
CTGF
DES
ECM
EGF
EGFR
ER
FGF
FSH
GH
GnRH
hCG
HGF
HIF
HPG
hPL
ICC
IgA
IGF
IGFBP
IgM
IR
Jak

B-cell CLL/lymphoma 2
Breast cancer 1
Basement membrane
Bromodeoxyuridine
Cluster of differentiation
Colony-stimulating factor
Connective tissue growth factor
Diethylstilbestrol
Extracellular matrix
Epidermal growth factor
Epidermal growth factor receptor
Estrogen receptor
Fibroblast growth factor
Follicle-stimulating hormone
Growth hormone
Gonadotropin-releasing hormone
Human chorionic gonadotropin
Hepatocyte growth factor
Hypoxia-inducible factor
Hypothalamic–pituitary–gonadal
Human placental lactogen
Interstitial cell of Cajal
Immunoglobulin A
Insulin-like growth factor
IGF-binding protein
Immunoglobulin M
Insulin receptor
Janus kinase

M.C. Johnson
Department of Anatomy, Physiology and Genetics, Uniformed
Services University, 4301 Jones Bridge Road, Bethesda, MD
20814, USA
e-mail:
M.L. Cutler (&)
Department of Pathology, Uniformed Services University, 4301
Jones Bridge Road, Bethesda, MD 20814, USA
e-mail:
© Springer International Publishing Switzerland 2016
I. Jatoi and A. Rody (eds.), Management of Breast Diseases, DOI 10.1007/978-3-319-46356-8_1

1


2

M.C. Johnson and M.L. Cutler

Ki67
LH
MMPs
OXT
PR
PRL
PRLR
PTH
PTHrP
Sca
SP

Stat
TDLU
TEB

A nuclear antigen in cycling cells
Luteinizing hormone
Matrix metalloproteinases
Oxytocin
Progesterone receptor
Prolactin
Prolactin receptor
Parathyroid hormone
Parathyroid hormone-related peptide
Stem cell antigen
Side population
Signal transducer and activator of transcription
Terminal ductal lobular unit
Terminal end bud

This chapter is a review of the development, structure, and
function of the normal human breast. It is meant to serve as a
backdrop and reference for the chapters that follow on
pathologies and treatment. It presents an overview of normal
gross anatomy, histology, and hormonal regulation of the
breast followed by a discussion of its structural and functional changes from embryonic development through postmenopausal involution. This section includes recent
information on some of the hormones, receptors, growth
factors, transcription factors, and genes that regulate this
amazing nutritive organ.
From the outset, it is important to keep in mind that
information in any discussion of human structure and

function is hampered by the limited methods of study
available. Observations can be made, but experimental
studies are limited. Therefore, much of what is discussed in
terms of the regulation of function has, of necessity, been
based on animal studies, primarily the mouse, and/or studies
of cells in culture. Significant differences between human
and mouse mammary glands are summarized at the end of
the chapter.
The number of genes and molecules that have been
investigated as to their role in the breast is immense. In
discussing each stage of breast physiology, we have included a summary of the important hormones and factors
involved. Some of the additional factors that have received
less attention in the literature are included in Table 1.1 in the
appendix. Table 1.2 in the appendix is a list of important
mouse gene knockouts and their effects on the mammary
gland.

1.1

Gross Anatomy of the Breast

Milk-secreting glands for nourishing offspring are present
only in mammals and are a defining feature of the class
Mammalia [1]. In humans, mammary glands are present in
both females and males, but typically are functional only in
the postpartum female. In rare circumstances, men have been
reported to lactate [2]. In humans, the breasts are rounded
eminences that contain the mammary glands as well as an
abundance of adipose tissue (the main determinant of size)
and dense connective tissue. The glands are located in the

subcutaneous layer of the anterior and a portion of the lateral
thoracic wall. Each breast contains 15–20 lobes that each
consist of many lobules (Fig. 1.1). At the apex of the breast
is a pigmented area, the areola, surrounding a central elevation, the nipple. The course of the nerves and vessels to
the nipple runs along the suspensory apparatus consisting of
a horizontal fibrous septum that originates at the pectoral
fascia along the fifth rib and vertical septa along the sternum
and the lateral border of the pectoralis minor [3].

1.1.1

Relationships and Quadrants

The breast is anterior to the deep pectoral fascia and is normally separated from it by the retromammary (submammary)
space (Fig. 1.1). The presence of this space allows for a
breast mobility relative to the underlying musculature: portions of the pectoralis major, serratus anterior, and external
oblique muscles. The breast extends laterally from the lateral


1

Anatomy and Physiology of the Breast

3

Table 1.1 Additional factors that have been studied in the breast
Factor

Experimental model

Function

References

Jak/Stat

Various

Signaling pathway used by PRL and other hormones

Review
[323]

Leptin

Cell culture

Promotes mammary epithelial cell proliferation

[324]

Hypoxia-inducible
factor (HIF) 1

Mice null for HIF 1

Required for secretory differentiation and activation and production and secretion of
milk of normal volume and composition

[146]

Notch signaling
pathway

Human epithelial cell
mammospheres in culture

Promotes proliferation of progenitor cells and promotes myoepithelial cell fate
commitment and branching morphogenesis

[325]

Wnt signaling
pathway

Human epithelial cell
mammospheres in culture

(May) play role in human mammary stem cell self-renewal, differentiation, and
survival

[326]

““

Rodents

Mammary rudiment development, ductal branching, and alveolar morphogenesis

[327]

GATA-3

Genetically altered mice

Promotes stem cell differentiation into luminal cells and maintains the luminal cell type
and is required for lactational sufficiency

[175, 176]

Msx2

Genetically altered mice

Transcription factor that promotes duct branching

[131]

Tbx3

Humans with ulnar mammary
syndrome and genetically altered
mice

Required for normal mammary development

[327]

Hedgehog
signaling pathway

Mice

Involved in every stage of mammary gland development

[328]

Hedgehog
signaling pathway

Genetically altered mice

Repression is required for mammary bud formation

[329]

Stat5

Humans and genetically altered
mice

Present in luminal cells and not myoepithelial cells. Regulates PRLR expression.
Promotes growth and alveolar differentiation during pregnancy and cell survival
during lactation

[256, 330]

Elf5

Mice

Required for growth and differentiation of alveolar epithelial cells in pregnancy and
lactation

[331]

HEX, a homeobox
gene

Normal human breast and normal
and tumor cell lines

Amount in nucleus much higher during lactation. May play role in lactational
differentiation

[332]

Table 1.2 Selected mammary gland-related mouse gene knockouts
Gene knocked out

Stage

Effect of knockout

Reference

LEF-1

Embryo

Fails to form first mammary buds

[333]

Tbx3

Embryo

Fails to form first mammary buds

[334]

Msx2

Embryo

Arrests at mammary sprout stage

[335]

PTHrP

Embryo

Failure of branching morphogenesis

[336]

c-Src

Puberty

Fewer TEBs and decreased ductal outgrowth

[337]

ERα

Puberty

Failed expansion of ductal tree

[214]

PR

Puberty

Failed lobuloalveolar development

[338]

PRL

Virgin adult

No lobular decorations

[339]

Stat5

Pregnancy

Incomplete mammary epithelial differentiation

[340]

Jak2

Pregnancy

Impaired alveologenesis and failure to lactate

[341]

α-lactalbumin

Lactation

Viscous milk

[342]

Whey acidic protein

Lactation

Pups die

[343]

OXT

Lactation

Inability to eject milk

[344]

CSF 1

Pregnancy

Incomplete ducts with precocious lobuloalveolar development

[345]

Cyclin D1

Pregnancy

Reduced acinar development and failure to lactate

[346]


4

M.C. Johnson and M.L. Cutler

Fig. 1.1 Sagittal section through
the lactating breast

edge of the sternum to the mid-axillary line and from the
second rib superiorly to the sixth rib inferiorly. An axillary
tail (of Spence) extends toward the axilla, or armpit.
For clinical convenience, the breast is divided into
quadrants by a vertical line and a horizontal line intersecting
at the nipple. The highest concentration of glandular tissue is
found in the upper outer quadrant. A separate central portion
includes the nipple and areola (Fig. 1.2). Positions on the
breast are indicated by numbers based on a clock face [4, 5].

Fig. 1.2 Breast quadrants: UO
upper outer, UI upper inner, LO
lower outer and LI lower inner

1.1.2

Nerve Supply

Innervation of the breast is classically described as being
derived from anterior and lateral cutaneous branches of
intercostal nerves four through six, with the fourth nerve the
primary supply to the nipple [6]. The lateral and anterior
cutaneous branches of the second, third, and sixth intercostal
nerves, as well as the supraclavicular nerves (from C3 and
C4), can also contribute to breast innervation [6]. Most of

1

Anatomy and Physiology of the Breast

the cutaneous nerves extend into a plexus deep to the areola.
The extent to which each intercostal nerve supplies the
breast varies among individuals and even between breasts in
the same individual. In many women, branches of the first
and/or the seventh intercostal nerves supply the breast.
Fibers from the third (most women [7]) and fifth intercostal
nerves may augment the fourth in supplying the nipple [8].
Sensory fibers from the breast relay tactile and thermal
information to the central nervous system. Cutaneous sensitivity over the breast varies among women, but is consistently greater above the nipple than below it. The areola and
nipple are the most sensitive and are important for sexual
arousal in many women [9]. This likely reflects the high
density of nerve endings in the nipples [10]. Small breasts
are more sensitive than large breasts [11], and women with
macromastia report relatively little sensation in the nipple–
areola complex [12].
While the apical surface of the nipple has abundant sensory
nerve endings, including free nerve endings and Meissner’s
corpuscles, the sides of the nipple and the areola are less highly
innervated. The dermis of the nipple is supplied by branched
free nerve endings sensitive to multiple types of input. Nipple
innervation is critical since normal lactation requires stimulation from infant suckling [13]. The peripheral skin receptors
are specialized for stretch and pressure.
Efferent nerve fibers supplying the breast are primarily
postganglionic sympathetic fibers that innervate smooth
muscle in the blood vessels of the skin and subcutaneous tissues. Neuropeptides regulate mammary gland secretion indirectly by regulating vascular diameter. Sympathetic fibers also

innervate the circular smooth muscle of the nipple (causing
nipple erection), smooth muscle surrounding the lactiferous
ducts and the arrector pili muscles [14]. The abundance of
sympathetic innervation in the breast is evident following
mammoplasty, when postsurgical complex regional pain
syndrome (an abnormal sympathetic reflex) is relieved by
sympathetic blockade of the stellate ganglion [15].
When milk is ejected by myoepithelial cell contraction,
the normally collapsed large milk ducts that end on the nipple
surface must open up to allow milk to exit. The opening of
these ducts is likely to be mediated by neurotransmitters that
are released antidromically from axon collaterals in response
to stimulation of nerve endings in the nipple. This local reflex
may also promote myoepithelial contraction. In stressful
situations, neuropeptide Y released from sympathetic fibers
may counteract this local reflex, resulting in a diminished
volume of milk available to the infant [16].

1.1.3

Vascular Supply

Arteries contributing to the blood supply of the breast
include branches of the axillary artery, the internal thoracic

5

artery (via anterior intercostal branches), and certain posterior intercostal arteries (Fig. 1.3). Of the anterior intercostal
arteries, the second is usually the largest and, along with
numbers three through five, supplies the upper breast, nipple,

and areola. The branches of the axillary artery supplying
breast tissue include the highest thoracic, lateral thoracic and
subscapular and the pectoral branches of the thoracoacromial
trunk [4]. Venous drainage of the breast begins in a plexus
around the areola and continues from there and from the
parenchyma into veins that accompany the arteries listed
above, but includes an additional superficial venous plexus
[17]. The arterial supply and venous drainage of the breast
are both variable. The microvasculature within lobules differs from that found in the denser interlobular tissue, with
vascular density (but not total vascular area) being higher in
the interlobular region than within the lobules [18]. Vascularity of the breast, as measured by ultrasound Doppler,
changes during the menstrual cycle and is greatest close to
the time of ovulation [19].

1.1.4

Lymphatic Drainage

Lymphatics of the breast drain primarily to the axillary
nodes, but also to non-axillary nodes, especially internal
mammary (aka parasternal) nodes located along the internal
mammary artery and vein. Some lymphatics travel around
the lateral edge of pectoralis major to reach the pectoral
group of axillary nodes, some travel through or between
pectoral muscles directly to the apical axillary nodes, and
others follow blood vessels through pectoralis major to the
internal mammary nodes. Internal mammary nodes are
located anterior to the parietal pleura in the intercostal
spaces. Connections between lymphatic vessels can cross the
median plane to the contralateral breast [20].

There are 20–40 axillary nodes that are classified into
groups based on their location relative to the pectoralis
minor. From inferior to superior, (a) the nodes below and
lateral to pectoralis minor comprise the low (level I) nodes,
(b) those behind the pectoralis minor make up the middle
(level II) nodes, and (c) those above the upper border of
pectoralis minor constitute the upper (level III) nodes
(Fig. 1.4). Lymphatic plexuses are found in the subareolar
region of the breast, the interlobular connective tissue, and
the walls of lactiferous ducts. Vessels from the subareolar
lymphatic plexus drain to the contralateral breast, the internal lymph node chain, and the axillary nodes [4]. Both
dermal and parenchymal lymphatics drain to the same
axillary lymph nodes irrespective of quadrant, with lymph
from the entire breast often draining through a small number
of lymphatic trunks to one or two axillary lymph nodes [21].
Sentinel lymph nodes are those that are the first stop
along the route of lymphatic drainage from a primary tumor


6

M.C. Johnson and M.L. Cutler

Fig. 1.3 Vascular supply of the breast. Arterial blood is supplied by
branches of the axillary artery (Lateral Thoracicand Pectoral Branch of
the Thoracoacromial Trunk). Additional blood supply is from Medial
Mammary Branches ofthe Internal Thoracic (Internal Mammary) artery

and from Lateral Branches of the Posterior Intercostal Arteries.Venous
drainage is via veins that parallel the arteries with the addition of a

superficial plexus (not shown)

[22]. Much of the information about breast lymphatic drainage has been derived from clinical studies aimed at identifying sentinel nodes and determining likely sites of
metastases (a topic beyond the scope of this chapter). These
studies often use the injection of radioactive tracer into a
lesion, but techniques vary as do results. It is generally
accepted that most breast tumors metastasize via lymphatics
to axillary lymph nodes. The degree to which metastasis
involves internal mammary nodes is debated. One study [23]
states that the rate of metastasis to internal mammary nodes
is less than 5 %, while another claims that over 20 % of
tumors drain at least in part to internal mammary nodes [24].
In women volunteers with normal breast tissue, isotope
injected into parenchyma or into subareolar tissue drained, at
least in part, into internal mammary nodes in 20–86 % of
cases [25]. Microinjection of dye directly into lymph vessels
of normal cadavers revealed that all superficial lymph vessels, including those in the nipple and areolar regions, enter a
lymph node in the axilla close to the lateral edge of the

pectoralis minor (group I). Superficial vessels run between
the dermis and the parenchyma, but some run through the
breast tissue itself to deeper nodes and into the internal
mammary system [26]. Drainage to internal mammary nodes
from small breasts (especially in thin and/or young women)
is more likely to pass into internal mammary nodes than is
drainage from large breasts [27].

1.1.5

Gross Anatomic Changes Throughout

the Life span

The breast of the newborn human is a transient slight elevation that may exude small amounts of colostrum-like fluid
known colloquially as “witch’s milk.” Human female and
male breasts are indistinguishable until puberty [28]. Puberty
begins with thelarche, the beginning of adult breast development. The age of thelarche is getting younger. Among
whites in 1970, the mean age was 11.5 years of age, but in


1

Anatomy and Physiology of the Breast

7

Fig. 1.4 Lymphatic drainage of the breast. Most drainage is into the
axillary nodes indicated as Level I, Level II and Level III, based on
their relationship to the Pectoralis Minor muscle. Level I nodes are

lateral to the muscle, LevelI I are behind it and Level III are medial to it.
Also note the Internal Mammary Nodes located just lateral to the edge
of the sternum and deep to the thoracic wall musculature

1997, it was 10 years of age. Among blacks, thelarche occurs
about one year earlier than in whites [29]. The first indication
of thelarche is the appearance of a firm palpable lump deep to
the nipple, the breast bud. It corresponds to stage II of the
Tanner [30] staging system. (Stage I is prepubertal; stage III
exhibits obvious enlargement and elevation of the entire
breast; stage IV, very transient, is the phase of areolar

mounding and it contains periareolar fibroglandular tissue;
stage V exhibits a mature contour and increased subcutaneous
adipose tissue). The human breast achieves its final external
appearance 3–4 years after the beginning of puberty [31].
Following puberty, the breast undergoes less dramatic

changes during each menstrual cycle (discussed in detail
later). The texture of the breast is least nodular just before
ovulation; therefore, clinical breast examinations are best
done at this time. In addition, the breast is less dense on
mammogram during the follicular phase. The volume of
each breast varies 30–100 mL over the course of the menstrual cycle. It is greatest just prior to menses and minimal
on day 11 [32]. The breast enlarges during pregnancy and
lactation, and the postlactational breast may exhibit stria
(stretch marks) and sag. The postmenopausal breast is often
pendulous.


8

1.2
1.2.1

M.C. Johnson and M.L. Cutler

Histology
Overview

The adult human breast is an area of skin and underlying
connective tissue containing a group of 15–20 large modified

sweat glands [referred to as lobes (Fig. 1.1)] that collectively
make up the mammary gland. The most striking thing about
breast morphology is its remarkable heterogeneity among
normal breasts, both within a single breast and between
breasts [33]. The glands that collectively make up the breast
are embedded in extensive amounts of adipose tissue and are
separated by bands of dense connective tissue (Fig. 1.5)
(suspensory or Cooper’s ligaments [6]) that divide it into
lobes [34] and extend from the dermis to the deep fascia.
Fig. 1.5 Low power micrograph
(50×) of an active (but not lactating) human breast. The dark line
outlines a portion of a lobule. Note
A the areolar connective tissue
within the lobule and between the
ductules, B the dense connective
tissue between lobules and C
adipose tissue. Some secretory
product has accumulated within
the ductules of the lobule

Fig. 1.6 Low power micrograph
(50×) of an active (but not lactating)
human breast. Arrows at A indicate
intralobular ducts (ductules) within
lobules. True acini are not present at
this stage. The arrow at B indicates
the lumen of a lactiferous
(interlobular) duct

The lobules within each lobe drain into a series of

intralobular ducts that, in turn, drain into a single lactiferous
duct (Fig. 1.6) that opens onto the surface of the nipple. The
part of each lactiferous duct closest to the surface of the
nipple is lined by squamous epithelium [35] that becomes
more stratified as it nears its orifice. In a non-lactating breast,
the opening of the lactiferous duct is often plugged with
keratin [4, 36]. Deep to the areola, the lactiferous ducts
expand slightly into a sinus that acts as a small reservoir
(Fig. 1.1).
The mammary gland is classified as branched tubuloalveolar, although true alveoli do not typically develop
until pregnancy. Individual lobules are embedded in a loose
connective tissue stroma that is highly cellular and responds
to several hormones [35]. Terminal ductal lobular units


1

Anatomy and Physiology of the Breast

9

Fig. 1.7 Intermediate power micrograph (100×) of an active (but not
lactating) human breast. A Terminal Ductal Lobular Unit (TDLU) and

its duct are outlined. Note the abundant adipose tissue and dense
irregular connective tissue surrounding the TDLU

(TDLUs) are considered to be the functional units of the
human mammary gland. Each TDLU consists of an
intralobular duct and its associated saccules (also called

ductules). These saccules differentiate into the secretory
units referred to as acini or alveoli [37]. The alveoli are
outpocketings along the length of the duct and at its terminus. A TDLU resembles a bunch of grapes [38] (Fig. 1.7).
Three-dimensional reconstruction of the parenchyma
from serial sections of human breast tissue [39] revealed no
overlap in territories drained by adjacent ducts. However, a
recent computer-generated 3-D model based on a single
human breast found that anastomoses do exist between
branching trees of adjacent ducts [40].
The ductwork of the breast has progressively thicker
epithelium as its tributaries converge toward the nipple. The
smallest ducts are lined with simple cuboidal epithelium,
while the largest are lined with stratified columnar epithelium [41]. The epithelial cells have little cytoplasm, oval
central nuclei with one or more nucleoli, and scattered or
peripheral chromatin [36].
The entire tubuloalveolar system, including each saccule,
is surrounded by a basement membrane (BM) (Fig. 1.8).
Between the luminal epithelial cells and the BM is interposed an incomplete layer of stellate myoepithelial cells. The
myoepithelial layer is more attenuated in the smaller branches of the ductwork and in the alveoli. Macrophages and
lymphocytes are found migrating through the epithelium
toward the lumen [42].

1.2.2

Nipple and Areola

The nipple and the areola are hairless [36]. Nipple epidermis
is very thin and sensitive to estrogen. Sweat glands and small
sebaceous glands (of Montgomery) are found in the areola
and produce small elevations on its surface. The skin of the

adult nipple and areola is wrinkled due to the presence of
abundant elastic fibers [4] and contains long dermal papillae.
Lactiferous ducts open on the surface of the nipple, and
parenchymal tissue radiates from it into the underlying connective tissue. The stroma of the nipple is dense irregular
connective tissue that contains both radial and circumferential smooth muscle fibers. Contraction of the smooth muscle
fibers results in erection of the nipple and further wrinkling of
the areola [4]. Nipple erection can occur in response to cold,
touch, or psychic stimuli. Smaller bundles of smooth muscle
fibers are located along the lactiferous ducts [43].

1.2.3

Parenchyma

1.2.3.1 Luminal Epithelial Cells
Luminal epithelial cells carry out the main function of the
breast: milk production. The secretory prowess of the
luminal epithelial cells is impressive. They can produce three
times their own volume per day. Luminal epithelial cells
have scant cytoplasm and a central, oval nucleus with marginal heterochromatin. They are cuboidal to columnar, and


10

M.C. Johnson and M.L. Cutler

Fig. 1.8 Intermediate power micrograph (200×) of an active (but not
lactating) human breast. The arrows labeled A indicate basement
membranes (BM) surrounding individual ductules. The letter B is in the
dense irregular connective tissue surrounding this lobule. Note the pale

elongated nuclei of fibroblasts and the collagen fibers surrounding the
letter B. The inset indicated by the rectangle is enlarged in the lower
right corner. Arrows in theinset indicate myoepithelial cells and the
chevron indicates a luminal epithelial cell

each cell has a complete lateral belt of occluding (tight)
junctions near its apex and E-cadherin (a transmembrane
protein found in epithelial adherens junctions) on its lateral
surfaces [44]. During lactation, luminal cells contain the
organelles typical of cells secreting protein, as well as many
lipid droplets for release into milk [36].

Myoepithelial cells utilize the adhesion molecule
P-cadherin [44] (a transmembrane protein), the knockout of
which results in precocious and hyperplastic mammary gland
development in mice [51]. They also express growth factor
receptors and produce matrix metalloproteinases (MMPs)
and MMP inhibitors that modify ECM composition. Cell–
cell contacts between the myoepithelial cells and their
luminal cell neighbors allow for direct signaling [52] between
the two cell types, and their basal location positions them to
mediate interactions between the luminal cells and the ECM.
In addition to contracting to express milk toward the
nipple, myoepithelial cells establish epithelial cell polarity
by synthesizing the BM. Specifically, they deposit fibronectin (a large glycoprotein that mediates adhesion), laminin
(a BM component that has many biologic activities), collagen IV, and nidogen (a glycoprotein that binds laminin and
type IV collagen). Human luminal cells cultured in a type I
collagen matrix form cell clusters with reversed polarity and
no BM [50]. Introducing myoepithelial cells corrects the

polarity and leads to the formation of double-layered acini
with central lumina. Laminin [53] is unique in its ability to
substitute for the myoepithelial cells in polarity reversal [50].
Other roles of the myoepithelial cell in the breast include
lineage segregation during development and promoting
luminal cell growth and differentiation [45, 54]. They also
play an active role in branching morphogenesis [55] and
even exhibit a few secretory droplets during pregnancy and
lactation [31]. The myoepithelial cell rarely gives rise to

1.2.3.2 Myoepithelial Cells
Myoepithelial cells surround the luminal cell layer (inset,
Fig. 1.8) and are located between it and the BM, which they
secrete [45]. In the ducts and ductules, myoepithelial cells
are so numerous that they form a relatively complete layer
[4, 46]. In alveoli, the myoepithelial cells form a network of
slender processes that collectively look like an open-weave
basket [35]. Myoepithelial cell processes indent the basal
surface of nearly every secretory cell [36] and contain parallel arrays of myofilaments and dense body features commonly found in smooth muscle cells. They also contain
smooth muscle-specific proteins and form gap junctions with
each other [47].
While myoepithelial cells exhibit many features of
smooth muscle cells, they are true epithelial cells. They
contain cytokeratins 5 and 14, exhibit desmosomes and
hemidesmosomes [48], and are separated from connective
tissue by a BM. Compared to luminal cells, they contain
higher concentrations of β-integrins (receptors that attach to
extracellular matrix (ECM) elements and mediate intracellular signals) [49, 50].

1

Anatomy and Physiology of the Breast

11

tumors itself [56] and is thought to act as a natural tumor Identification of Mammary Stem Cells
suppressor [45].
If mature luminal human cells express certain markers and
myoepithelial cells express others, then epithelial cells with
1.2.3.3 Stem Cells
little or none of either set of markers are likely to be more
primitive. If mammary gland cells are separated by flow
Definitions and Terms
cytometry and subpopulations are plated on collagen matriThe idea of a population of mammary gland stem cells [57] ces, a subpopulation can be identified that produces colonies
has existed since the 1950s. These cells would give rise containing both luminal and myoepithelial cells [67].
Human mammary stem cells are positive for both keratins
either to two daughter cells or to one stem cell and one
lineage-specific progenitor cell that would, in turn, give rise 19 and 14 and are capable of forming TDLU-like structures
in 3-D gel cultures. They can give rise to K19/K14 +/−, −/−
to either luminal cells or myoepithelial cells [58].
A rigorous definition of a tissue-specific stem cell (both are luminal), and −/+ (myoepithelial) cells, each of
requires that it meets five criteria [59]. It must (1) be mul- which are lineage-restricted progenitors [68]. The embryonic
tipotential, (2) self-renew, (3) lack mature cell lineage marker CD133 is detected in the mammary gland also
markers, (4) be relatively quiescent, and (5) effect the serving as a marker of mammary stem cells [69].
The ability of certain cells to pump out loaded Hoechst
long-term regeneration of its “home” tissue in its entirety.
Much of the mammary cell literature takes liberty with these 33342 dye allows them to be separated by flow cytometry
criteria, often applying the term “stem cell” to cells that can into a “side population” (SP), claimed by some to be a
give rise to either (but not both) of the two parenchymal cell population of stem cells. However, in the mammary gland,

types. Some still argue [60] that the existence of true human the evidence that the SP is enriched for stem cells is only
mammary epithelial stem cells in adults has not been correlative. Cells have been identified as quiescent stem cells
based on their retention of BrdU incorporated during a prior
unequivocally demonstrated.
period of proliferation plus their lack of both luminal and
myoepithelial cell markers. Using this method, 5 % of the
Structure and Function of Mammary Stem Cells
cells in the mouse mammary gland are quiescent stem cells.
A cell that stains poorly with osmium [61] in mouse mam- They express Sca-1 (a stem cell marker), are progesterone
mary epithelium has been equated to the mammary gland receptor (PR) negative, and are located within the luminal
stem cell. These cells are present at all stages of differenti- cell layer [70].
Lineage-tracing experiments can follow stem and proation and undergo cell division shortly after being placed in
culture, even in the presence of DNA synthesis inhibitors. genitor cell fate during development and tissue reorganizaThey do not synthesize DNA in situ or in vitro, but do tion in mice using promoters of genes linked to a specific
incorporate the nucleotide precursors needed for RNA syn- lineage ex: Elf5, the gene linked to luminal progenitors
thesis. In mice, stem cell daughter cells functionally differ- driving visual markers. The results obtained with this
entiate in explant cultures in the presence of lactogenic approach called into question the existence of bipotent
mammary stem cells, given the apparent disparity between
hormones [62].
Stem cells are distinguishable phenotypically from results obtained with transplantation versus lineage-tracing
mammary epithelial progenitor cells. The progenitor cells assays. This suggested that tissue disruption and sorting of
produce adherent colonies in vitro, are a rapidly cycling cells prior to implantation may activate them or contribute to
population in the normal adult, and have molecular features their “stemness.” While it has been postulated that bipotent
indicating a basal position. Stem cells have none of those stem cells detected in the embryo no longer function in the
properties, and in serial culture studies, murine stem cells postnatal animal, recent evidence detected bipotent stem
disappear when growth stops [63]. Murine mammary gland cells participating in epithelial differentiation in the adult
cells transplanted into host tissue will reconstitute a func- mammary gland [71].
Examples of Cells Referred to as Mammary Stem Cells:
tional mammary ductal tree that is morphologically indistinguishable from the normal gland [64]. Furthermore, a
fully differentiated mammary gland can be derived from a • Human mammary epithelial cells with neither luminal
cell nor myoepithelial cell markers.

single murine stem cell clone [65, 66].


12

• Subpopulations of mammary gland cells separated by
flow cytometry that produce colonies containing both
luminal and myoepithelial cells [67].
• Human mammary stem cells that are capable of forming
TDLU-like structures in 3-D gel cultures. They can give
rise to K19/K14 +/−, −/− (both are luminal), and −/+
(myoepithelial) cells, each of which are lineage-restricted
progenitors [68].
• Mammary cells that pump out loaded Hoechst 33342 dye
and separate by flow cytometry into a “side population”
(SP). However, in the mammary gland, the evidence that
the SP is enriched for stem cells is only correlative.
• Mammary cells that are quiescent, based on their retention of BrdU that was incorporated during a prior period
of proliferation, that also lack both luminal and myoepithelial cell markers. By this method, 5 % of mouse
mammary epithelial cells are quiescent stem cells. They
also express Sca-1 (a stem cell marker), are progesterone
receptor (PR) negative, and are located within the luminal cell layer [69].
• Cell fate mapping studies in mice using multicolor
reporters indicated the presence of bipotent stem cells
that coordinate remodeling in the adult mammary gland
but demonstrate that both stem and progenitor cells drive
morphogenesis during puberty [71].
• Breast cancer stem cells (BCSCs) are defined as a subset
(1–5 %) of CD44+/CD24-/lin- cells from primary human
tumors that can form tumors in athymic mice [72]. These

cells typically express aldehyde dehydrogenase (ALDH)
which correlates with level of HER2 [73].
• CD133 is detected on stem cells in the mammary gland
[69]. It is identified as stem cell marker in multiple tumor
types including triple-negative breast cancer [74, 75],
often correlating with the level of vascular mimicry [76].
Location of Mammary Stem Cells
The concentration of stem cells in the human is highest in
ducts [68]. They tend to be quiescent and surrounded by
patches of proliferating cells and differentiated progeny [77].
Stem cells are believed to be the pale cells intermediate in
position between the basal and the luminal compartments of
the mammary epithelium. However, a cell line has been
isolated from the luminal compartment in humans that can
generate itself, secretory cells, and myoepithelial cells [55].
Classification of Mammary Stem Cells
Human stem cells and progenitors are classified into several
ways. One classification system is based on steroid hormone
receptors: Estrogen receptor (ER)α/PR-negative stem cells
function during early development, and ERα/PR-positive

M.C. Johnson and M.L. Cutler

stem cells are required for homeostasis during menstrual
cycling [77]. The existence of receptor (ER)α/PR- stem cells
suggests the need for paracrine mechanisms for regulation by
hormones, and in fact, ERα/PR + act as sensors to relay
hormonal cues to the (ER)α/PR- cells [78, 79]. In another
scheme, stem cells in nulliparous women are classified as
type one, while stem cells found in parous women are classified as type two. Parity-induced (type two) murine mammary epithelial cells are able to form mammospheres in

culture and, when transplanted, establish a fully functional
mammary gland [80]. These cells reside in the luminal layer
of the ducts and contribute to secretory alveoli that appear in
pregnancy [81]. The nulliparous type is more vulnerable to
carcinogenesis [82]. A third scheme [83] classifies the
mammary progenitors into three types: (1) a
luminal-restricted progenitor that produces only daughter
cells with luminal cell markers, (2) a bipotent progenitor (the
“stem cell” described by other investigators) that produces
colonies with a core of luminal cells surrounded by cells with
the morphology and markers typical of myoepithelial cells,
and (3) a progenitor that generates only myoepithelial cells.
A special stem cell (like) type has been identified in
multiparous human females. It is pregnancy-induced, does
not undergo apoptosis following lactation, and is capable of
both self-renewal and production of progeny with diverse
cellular fates [84]. This cell type increases to constitute as
much as 60 % of the epithelial cell population in multiparous women and may be related to the parity-related
resistance to breast cancer [82].
Factors Regulating Stem Cells
The development of suspension cultures in which human stem
cells form “mammospheres” [85] has facilitated the study of
the various pathways regulating the self-renewal and differentiation of normal mammary stem and progenitor cells [86].
A specific cell’s “stemness” decreases as that cell becomes
more differentiated. Stem cells can self-renew and proliferate
within their niche, where they are maintained in their undifferentiated state by cell–ECM and cell–cell interactions. These
interactions involve integrins and cadherins, respectively.
Wnt/β-catenin signaling is a regulator of self-renewal in stem
cells [87, 88]. Wnt4 is a regulator of stem cell proliferation
downstream of progesterone as is RANKL, which has been

implicated as a paracrine mediator [89–91]. Chromatin regulators can also affect the balance between self-renewal and
differentiation. For example, the histone methylation reader
Pygo2 is a Wnt pathway coactivator that facilitates binding of
β-catenin to Notch3 to suppress luminal and alveolar differentiation by coordinating these pathways [92].
Lineage-tracing experiments determined that the Notch
pathway is critical in the luminal lineage. Notch3-expressing


1

Anatomy and Physiology of the Breast

cells are luminal progenitors that give rise to ER+ and ERductal progeny [93], which exhibit functional similarity to
parity-induced cells that contribute to secretory alveoli.
HER2 is required for early stages of mammary development [94, 95] and it is an important regulator of CSCs [96].
It can be targeted by trastuzumab, and the success of trastuzumab therapy in tumors where HER2 is not amplified is
thought to occur through targeting CSCs [97, 98].
Hormones and cytokines stimulate proliferation of stem
cells and this has implications for the development of breast
cancer [90]. Obesity is associated with the incidence and
mortality of breast cancer [99, 100], and cytokine-mediated
increase in stem cell number may be mechanistically
involved. Pituitary growth hormone, acting via IGF-1 as
well as through receptor-mediated JAK-Stat signaling, is
required for mammary development as is IGF-1 [101, 102].
IGF-1 treatment increases the number of mammary stem
cells in rodents, and IGF-1R expression correlates with the
risk of breast cancer in humans [103]. Leptin increases
mammary stem cell self-renewal, and its level in human
serum correlates with obesity [104]. An increase in the

number of cycling cells in normal breast tissue in premenopausal women is associated with an increased risk of
developing breast cancer [105], suggesting that environmental stimulation of human mammary progenitor cells may
contribute to the subsequent development of breast cancer.

1.2.4

Basement Membrane

The luminal cells of the mammary gland rest on a BM (except
where myoepithelial cell processes intervene). Components
of the mammary gland BM include collagen type IV, laminin, nidogens 1 and 2, perlecan, and fibronectin [106–108].
All of these components are found within the BMs of ducts,
lobules, and alveoli in both the human and the mouse.
Many mammary epithelial cell functions require a BM
including milk production [109], suppression of programmed cell death [110], interaction with prolactin
(PRL) [111], and the expression of ERα needed to respond
to estrogen. Reconstituted BM (or collagen type IV or
laminin I) and lactogenic hormones can substitute for the
BM requirement for ER expression [112]. Precise contact
between epithelial cells and their underlying BM is critical
for the maintenance of tissue architecture and function. For
example, cultured mammary epithelial cells unable to anchor
normally to the laminin in their BM have disrupted polarity
and are unable to secrete β-casein, the most abundant milk
protein [113]. Laminin activates expression of the β-casein
gene [114]. In tissue culture, mammary epithelial cells
require laminin and specific β1-integrins for survival [107,
115]. Nidogen-1 connects laminin and collagen networks to
each other, is essential for BM structural integrity [107], and

13

promotes lactational differentiation [116]. Integrins are
essential for cell–BM interactions that are required for lactogenic cellular differentiation [117]. β1-integrin is required
for alveolar organization and optimal luminal cell proliferation [118] and, along with laminin, is required for end bud
growth during puberty [119]. The fibronectin-specific integrin is localized to myoepithelial cells and is thought to be
required for hormone-dependent cell proliferation [120].
The ability to culture cells in 3-D using synthetic BM
culture systems, such as Matrigel™, has opened the door to
investigations of normal, as well as cancerous breast physiology [121]. Normal mammary epithelial cells seeded into
Matrigel™ form small cell masses, develop apicobasal
polarity, secrete ECM components basally, and develop
apical Golgi and junctional complexes. The cell masses form
a lumen by cavitation involving the removal of central cells
by programmed cell death [122] and, in the process of
becoming differentiated, form tight junctions prior to
secreting milk [123].

1.2.5

Stroma

There are three types of connective tissue in the breast: loose
connective tissue within lobules (intralobular), dense irregular connective tissue between lobules (interlobular), and
adipose tissue (also interlobular) (Fig. 1.5). The dense connective tissue contains thick bundles of collagen and elastic
fibers that surround the individual lobular units. Breast
stroma is not a passive structural support; epithelial–stromal
interactions play key roles in development and differentiation. The intralobular loose connective tissue is in close
relationship to the ductules and alveoli of the mammary
gland and is responsive to hormones.

1.2.5.1 Cells in Breast Stroma
While cells found in the interlobular connective tissue are
primarily fibroblasts or adipocytes, the intralobular connective tissue also contains macrophages, eosinophils, lymphocytes, plasma cells, and mast cells.
Fibroblasts form a basket-like layer around the human
TDLU external to its BM [124] (Fig. 1.9). In the intralobular
connective tissue, fibroblasts have attenuated cytoplasmic
processes that form a network via cell–cell connections [33].
The connections serve to link the fibroblasts adjacent to the
BM with those found within the lobular stroma. Mammary
gland fibroblasts have ultrastructural features typical of
synthetically active cells. Other cells in the intralobular
connective tissue are interspersed within the fibroblast network such that cell–cell interaction is facilitated. Intralobular
fibroblasts are CD34 (a marker for early stem-like cells)
positive [35].


14

M.C. Johnson and M.L. Cutler

Fig. 1.9 High power micrograph
(400×) of an active (but not
lactating) human breast. Arrows
labeled A indicate nuclei of fibro
blasts surrounding a ductule.
Arrows labeled B indicate
collagen fiber bundles and the
ovals surround plasma cells

Two populations of human mammary gland fibroblasts
can be distinguished based on staining for the cell surface
enzyme dipeptidyl peptidase IV, an enzyme implicated in
breast cancer metastasis. Intralobular fibroblasts are negative
for this enzyme, but interlobular fibroblasts are positive
[125]. Human breast fibroblasts have the ability to inhibit the
growth of epithelial cells. If the ratio of fibroblasts to
epithelial cells is high, however, the fibroblasts enhance
epithelial proliferation [126, 127].
Adipocytes (Fig. 1.5) are common in the breast. High
breast density on mammogram (negatively correlated with
fat) is a risk factor for breast cancer [102]. In pregnant
women, the adipocytes are closer to the epithelium and the
number of fat-filled cells is markedly reduced throughout
pregnancy and lactation. Adding adipocytes to murine
epithelial cells in vitro enhances mammary cell growth and
seems to be required for the synthesis of casein.
Macrophages are localized near the epithelium during
certain stages of breast development and have been shown to
be critical for proper duct elongation. The macrophage
growth factor, CSF1, promotes murine mammary gland
development from branching morphogenesis to lactation
[128]. Macrophages may play a role in both angiogenesis
and the ECM remodeling required during morphogenesis
[129]. They are localized in close proximity to developing
alveoli during pregnancy and are present during involution,
where they likely help clear out milk lipid droplets and/or
apoptotic debris [130]. Eosinophils are present during

postnatal development, where they are believed to interact

with macrophages to induce proper branching morphogenesis [131].
Lymphocyte migration into the mammary gland during
lactation is facilitated by specific adhesion molecules located
on the endothelial cells. Lymphocytes themselves can be
found in milk. Plasma cells derived from B lymphocytes are
abundant in the stroma before and during lactation when
they secrete antibodies that are taken up by the epithelial
cells and secreted into milk [132].
Mast cells contain several potent mediators of inflammation including histamine, proteinases, and several cytokines. Nevertheless, the precise functions of mast cells are
still unknown [133]. Since mast cells are associated with
bundles of collagen in human breast stroma, they may play a
role in collagen deposition [134].
Recently, two additional stromal cell types have been
identified: the interstitial cell of Cajal (ICC) and the ICC-like
cell. These cells have two or three long, thin moniliform
processes [135] and establish close contacts with various
immunoreactive cells, including lymphocytes, plasma cells,
macrophages, and mast cells [136]. ICCs from the breast form
“intercellular bridges” in vitro [137]. They have caveolae,
overlapping processes, stromal synapses (close contacts), and
gap junctions. They also exhibit dichotomous branching.
Collectively, the ICCs make up a labyrinthine system that
may play a pivotal role in integrating stromal cells into a
functional assembly with a defined 3-D structure [138].


1

Anatomy and Physiology of the Breast

1.2.5.2 Extracellular Matrix
The 3-D organization of the ECM affects many aspects of
cell behavior: shape, proliferation, survival, migration, differentiation, polarity, organization, branching, and lumen
formation [131]. Two principal ways that the ECM can
affect cell behavior are to (1) harbor various factors and/or
their binding proteins to be released when needed and
(2) directly regulate cell behavior via cell–ECM interactions
[111].
Stromal fibronectin and its receptor, α5β1-integrin, play
an important role in ovarian hormone-dependent regulation
of murine epithelial cell proliferation. The fibronectin
receptor is more closely correlated with proliferation and
more rapidly regulated by estrogen and progesterone than is
fibronectin itself. Thus, it is likely that the receptor, rather
than fibronectin, is hormonally regulated. Mouse fibronectin
levels increase threefold between puberty and sexual maturity and remain high during pregnancy and lactation [139].
Integrins, the major ECM receptors, link the ECM to the
actin cytoskeleton and to signal transduction pathways [140]
involved in directing cell survival, proliferation, differentiation, and migration. They mediate interactions between
stroma and parenchyma. Specific integrin functions in the
human mammary gland have been reviewed elsewhere [141].
Proteoglycans, large heavily glycosylated glycoproteins,
are abundant in breast ECM and correlate with increased
mammographic density, a risk factor for breast cancer [142].
They are also important in coordinating stromal and
epithelial development and mediating cell–cell and cell–
matrix interactions. Several regulatory proteins in the
mammary gland bind to proteoglycan glycosaminoglycans,
including fibroblast growth factors (FGFs), epidermal
growth factors (EGFs), and hepatocyte growth factor

(HGF) [143].

1.3

1.3.1

Synopsis of Hormones and Other Factors
that Regulate Breast Structure
and Function
Hormones

This segment is a brief overview of reproductive hormonal
events in the female, particularly as they affect the breast.
Details of endocrine involvement in each phase of breast
development and function are discussed in Sect. 1.4.
The hormonal control of human reproduction involves a
hierarchy consisting of the hypothalamus, the anterior pituitary gland and the gonads: the hypothalamic–pituitary–gonadal (HPG) axis. In the female, the main hormones
involved are (1) gonadotropin-releasing hormone (GnRH)
from the hypothalamus, (2) luteinizing hormone (LH) and
follicle-stimulating hormone (FSH) from the pituitary, and

15

(3) estrogen and progesterone, steroid hormones derived
from cholesterol and made in the ovary (Fig. 1.10). The
levels of these hormones vary dramatically throughout each
menstrual cycle (Fig. 1.11), as well as during the various
stages of a woman’s lifetime.
GnRH causes the anterior pituitary gland to secrete LH
and FSH. The hypothalamus releases GnRH in a pulsatile

manner from axon terminals of neurons in the medial basal
hypothalamus [144]. Pulsatile release of GnRH into the
hypothalamo-hypophyseal portal system, which carries it
directly to the pituitary gland, is essential to its function.
LH and FSH promote new ovarian follicle growth during
the first 11–12 days of the menstrual cycle. The follicle, in
turn, secretes both steroid hormones, estrogen and progesterone. Estrogen and progesterone are transported in the
blood bound to proteins, primarily albumin and specific
hormone binding globulins [145]. Just before ovulation,
there is a sudden marked increase in both LH and FSH, a
surge that leads to ovulation and the subsequent formation of
the corpus luteum from the follicle.
Between ovulation and the beginning of menstruation, the
corpus luteum secretes large amounts of estrogen and progesterone. These hormones have a negative feedback effect
on secretion of LH and FSH in the pituitary gland, as well as
GnRH secretion in the hypothalamus (Fig. 1.11). Estrogen
primarily promotes the development of female secondary sex
characteristics, including the breast. Progesterone mainly
prepares the uterus for the receipt and nurture of the embryo
and fetus and prepares the breast for lactation. During
pregnancy, estrogen and progesterone are secreted primarily
by the placenta. The main effects of estrogen on the breast
are (1) stromal tissue development, (2) growth of breast
ductwork, and (3) fat deposition [145]. Progesterone is
required for lobuloalveolar differentiation of the breast
[146].
These steroid hormones bind to receptors that belong to a
superfamily of related receptors. The ER is an intracellular
receptor that functions as a DNA-binding transcription factor
[147, 148]. There are two forms of ER: ERα and ERβ that are

coded on different genes [149]. Estrogen-binding affinity is
high at both receptors and both are expressed in the breast. In
the normal human breast, ERα is expressed in approximately
15–30 % of luminal epithelial cells [150], whereas ERβ is
found in myoepithelial cells and stromal cells [147]. Estrogen
binds to the ER and the ER–estrogen complex translocates to
the nucleus of the cell, where it binds to DNA and effects
transcriptional changes leading to alterations in cell function.
ER signaling can also act in a non-classical pathway by
interacting with other transcription factors bound to promoters of responsive genes [151]. ERα–estrogen complexes
activate gene transcription, while ERβ–estrogen complexes
can either activate or inhibit transcription [147, 152]. In mice,
binding of estrogen to ERα stimulates mammary cell