Chapter 087. Gastrointestinal Tract Cancer (Part 4) ppt

Chapter 087. Gastrointestinal
Tract Cancer
(Part 4)

Several additional etiologic factors have been associated with gastric
carcinoma. Gastric ulcers and adenomatous polyps have occasionally been linked,
but data on a cause-and-effect relationship are unconvincing. The inadequate
clinical distinction between benign gastric ulcers and small ulcerating carcinomas
may, in part, account for this presumed association. The presence of extreme
hypertrophy of gastric rugal folds (i.e., Ménétrier's disease), giving the impression
of polypoid lesions, has been associated with a striking frequency of malignant
transformation; such hypertrophy, however, does not represent the presence of true
adenomatous polyps. Individuals with blood group A have a higher incidence of
gastric cancer than persons with blood group O; this observation may be related to
differences in the mucous secretion, leading to altered mucosal protection from
carcinogens. A germline mutation in the E-cadherin gene, inherited in an
autosomal dominant pattern and coding for a cell adhesion protein, has been
linked to a high incidence of occult gastric cancers in young asymptomatic
carriers. Duodenal ulcers are not associated with gastric cancer.
Clinical Features
Gastric cancers, when superficial and surgically curable, usually produce no
symptoms. As the tumor becomes more extensive, patients may complain of an
insidious upper abdominal discomfort varying in intensity from a vague,
postprandial fullness to a severe, steady pain. Anorexia, often with slight nausea,
is very common but is not the usual presenting complaint. Weight loss may
eventually be observed, and nausea and vomiting are particularly prominent with
tumors of the pylorus; dysphagia and early satiety may be the major symptoms
caused by diffuse lesions originating in the cardia. There are no early physical
signs. A palpable abdominal mass indicates long-standing growth and predicts
regional extension.
Gastric carcinomas spread by direct extension through the gastric wall to

the perigastric tissues, occasionally adhering to adjacent organs such as the
pancreas, colon, or liver. The disease also spreads via lymphatics or by seeding of
peritoneal surfaces. Metastases to intraabdominal and supraclavicular lymph nodes
occur frequently, as do metastatic nodules to the ovary (Krukenberg's tumor),
periumbilical region ("Sister Mary Joseph node"), or peritoneal cul-de-sac
(Blumer's shelf palpable on rectal or vaginal examination); malignant ascites may
also develop. The liver is the most common site for hematogenous spread of
tumor.
The presence of iron-deficiency anemia in men and of occult blood in the
stool in both sexes mandates a search for an occult gastrointestinal tract lesion. A
careful assessment is of particular importance in patients with atrophic gastritis or
pernicious anemia. Unusual clinical features associated with gastric
adenocarcinomas include migratory thrombophlebitis, microangiopathic hemolytic
anemia, and acanthosis nigricans.
Diagnosis
A double-contrast radiographic examination is the simplest diagnostic
procedure for the evaluation of a patient with epigastric complaints. The use of
double-contrast techniques helps to detect small lesions by improving mucosal
detail. The stomach should be distended at some time during every radiographic
examination, since decreased distensibility may be the only indication of a diffuse
infiltrative carcinoma. Although gastric ulcers can be detected fairly early,
distinguishing benign from malignant lesions radiographically is difficult. The
anatomic location of an ulcer is not in itself an indication of the presence or
absence of a cancer.
Gastric ulcers that appear benign by radiography present special problems.
Some physicians believe that gastroscopy is not mandatory if the radiographic
features are typically benign, if complete healing can be visualized by x-ray within
6 weeks, and if a follow-up contrast radiograph obtained several months later
shows a normal appearance. However, we recommend gastroscopic biopsy and
brush cytology for all patients with a gastric ulcer in order to exclude a

malignancy. Malignant gastric ulcers must be recognized before they penetrate
into surrounding tissues, because the rate of cure of early lesions limited to the
mucosa or submucosa is >80%. Since gastric carcinomas are difficult to
distinguish clinically or radiographically from gastric lymphomas, endoscopic
biopsies should be made as deeply as possible, due to the submucosal location of
lymphoid tumors.
The staging system for gastric carcinoma is shown in Table 87-3.
Table 87-3 Staging System for Gastric Carcinoma

Data from ACS
Stage

TNM Features No.
of Cases, %

5-
Year
Survival, %

0 TisN0M0

Node negative;
limited to mucosa
1 90
IA T1N0M0

Node negative;
invasion of lamina
propria or submucosa
7 59

IB T2N0M0

Node negative;
invasion of muscularis
propria
10 44
II T1N2M0
T2N1M0

Node positive;
invasion beyond mucosa
but within wall
or
T3N0M0

Node negative;
extension through wall
17 29
IIIA T2N2M0
T3N1-
2M0
Node positive;
invasion of muscular
is
propria or through wall
21 15
IIIB T4N0-
1M0
Node negative;
adherence to surrounding

tissue
14 9
IV T4N2M0

Node positive;
adherence to surrounding
tissue
or
T1-4N0-
2M1
Distant metastases

30 3

Note: ACS, American Cancer Society.