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. . Chapter 087. Gastrointestinal Tract Cancer (Part 4) Several additional etiologic factors have been associated with gastric. 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. 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