Chapter 085. Neoplasms of the Lung (Part 1) pps

Chapter 085. Neoplasms of the Lung
(Part 1)

Harrison's Internal Medicine > Chapter 85. Neoplasms of the Lung
The Magnitude of the Problem
In 2007, primary carcinoma of the lung affected 114,760 males and 98,620
females in the United States; 86% die within 5 years of diagnosis, making it the
leading cause of cancer death in both men and women. The incidence of lung
cancer peaks between ages 55 and 65 years. Lung cancer accounts for 29% of all
cancer deaths (31% in men, 26% in women). Lung cancer is responsible for more
deaths in the United States each year than breast cancer, colon cancer, and prostate
cancer combined; more women die each year of lung cancer than of breast cancer.
The age-adjusted lung cancer death rate in males is decreasing, but in females it is
stable or still increasing. These death rates are related to smoking; smoking
cessation efforts begun 40 years ago in men are largely responsible for the change
in incidence and death rates. However, women started smoking in substantial
numbers about 10–15 years later than men; smoking cessation efforts need to
increase for women. The 5-year overall lung cancer survival rate (15%) has nearly
doubled in the past 30 years. The improvement is due to advances in combined-
modality treatment with surgery, radiotherapy, and chemotherapy. The
International Agency for Research on Cancer estimates that there will be over 1.18
million deaths from lung cancer worldwide in 2007, which will rise to 10 million
deaths per year by 2030. This represents one lung cancer case for every 3 million
cigarettes smoked. Thus, primary carcinoma of the lung is a major health problem
with a generally grim prognosis.
Pathology
The term lung cancer is used for tumors arising from the respiratory
epithelium (bronchi, bronchioles, and alveoli). Mesotheliomas, lymphomas, and
stromal tumors (sarcomas) are distinct from epithelial lung cancer. Four major cell
types make up 88% of all primary lung neoplasms according to the World Health
Organization classification (Table 85-1). These are squamous or epidermoid

carcinoma, small cell (also called oat cell) carcinoma, adenocarcinoma (including
bronchioloalveolar), and large cell carcinoma. The remainder include
undifferentiated carcinomas, carcinoids, bronchial gland tumors (including
adenoid cystic carcinomas and mucoepidermoid tumors), and rarer tumor types.
The various cell types have different natural histories and responses to therapy,
and thus a correct histologic diagnosis by an experienced pathologist is the first
step to correct treatment. In the past 25 years, adenocarcinoma has replaced
squamous cell carcinoma as the most frequent histologic subtype, and the
incidence of small cell carcinoma is on the decline.
Table 85-1 Frequency, Age-
Adjusted Incidence, and Survival Rates for
Different Histologic Types of Lung Cancer
a


Histologic Type of
Thoracic Malignancy
Frequency,
%
Age-
Adjusted
Rate
5-Year
Survival Rate
(All Stages)
Adenocarcinoma (and
all subtypes)
32 7 17
Bronchioloalveolar
carcinoma

3 1.4 42
Squamous cell
(epidermoid) carcinoma
29 15 15
Small cell carcinoma 18 9 5
Large cell carcinoma 9 5 11
Carcinoid 1.0 0.5 83
Mucoepidermoid
carcinoma
0.1 <0.1 39
Adenoid cystic
carcinoma
<0.1 <0.1 48
Sarcoma and other soft
tissue tumors
0.1 0.1 30
All others and
unspecified carcinomas
11.0 6 NA
Total 100 52 14

a
Data on histology frequency and age-
adjusted incidence rates per 100,000
U.S. population are from 60,514 cases of invasive lung cancer involving all races
and both sexes obtained from the data for 1983–1987 of the S
urveillance,
Epidemiology, and End Results (SEER) Program of the National Cancer Institute;
5-
year relative survival rates for all stages, all races, and both sexes are from the

SEER data on 87,128 carcinomas, 1978–1986. NA, not available.
Source: Summarized from Travis et al: Cancer 75:191, 1995.