Gastric carcinoma

* Epidemiology. Carcinoma is the most common malignant tumor of stomach (90% to 95%). Next in order of frequency are lymphomas (4%), carcinoids (3%), and mesenchymal tumors (2%). Gastric carcinoma is the second most common tumor in the world. Its incidence, however, varies widely, being particularly high in countries such as Japan. Male-to-female ratio of about 2:1.

* Pathogenesis of Gastric Cancer H. pylori Genetic factors Gastric Cancer Diet Precancerous changes

1. Helicobacter pylori Infection. Chronic infection with H. pylori generally increases the risk for developing gastric carcinoma by five- to six-fold. The bacterial infection causes chronic gastritis, followed by atrophy, intestinal metaplasia, dysplasia, and carcinoma.

2. Diet: • Nitrites derived from nitrates (preserved food). • Smoked and salted foods, pickled vegetables, chili peppers. • Lack of fresh fruit and vegetables.

3. Genetic factors: Slightly increased risk with blood group A. Family history of gastric cancer.

4. Precancerous lesions: 1. Gastric dysplasia: - About 10% of these cases progress to gastric carcinoma specially high-grade dysplasia. 2. Atrophic gastritis: which associated with intestinal metaplasia. 3. Chronic gastric peptic ulcer. 4. Gastric adenoma.

* Morphology of gastric carcinoma: The location of gastric carcinomas within the stomach is as follows: Pylorus and antrum, 50% to 60%. The remainder in the body and fundus: 25%. The lesser curvature is involved in about 40% and the greater curvature in 12%. Thus, a favored location is the lesser curvature of the antropyloric region.

* Gross morphology of gastric carcinoma: A. Polypoid (fungating): forming a fungating irregular hard mass projecting into the gastric lumen. B. Infiltrative: Localized. Diffuse (linnitus plastica). C. Ulcerative: forming malignant ulcer.

Polypoid (fungating)

Linnitus plastica

Ulcerating (malignant ulcer)

* Histologic subtypes of gastric carcinoma: 1. Intestinal type: - Composed of neoplastic intestinal glands resembling those of colonic adenocarcinoma which permeate the gastric wall. 2. Diffuse type (Signet ring): - Composed of malignant mucous cells, which generally do not form glands, but rather permeate the gastric wall as individual cells.

1. Gastric carcinoma; Intestinal type:

1. Gastric carcinoma; Intestinal type:

Gastric carcinoma: diffuse type.

* Complications of gastric carcinoma: GIT bleeding. Gastric obstruction. Gastric perforation specially in the ulcerative type. Spread: Direct. Lymphatic: especially to the left supraclavicular lymph node (Virchow’s sign). Blood. Transcoelomic (Krukenberg’s tumor).

* Clinical Features of gastric carcinoma: Gastric carcinoma is an insidious disease that is generally asymptomatic until late in its course. The symptoms include weight loss, abdominal pain, anorexia, vomiting, altered bowel habits, and less frequently dysphagia, anemic symptoms, and hemorrhage. As these symptoms are essentially non-specific, early detection of gastric cancer is difficult.

* Diagnosis of gastric adenocarcinoma: 1. Clinical features: 2. Endoscopy: for evaluating both gross and microscopic appearance of the tumor by taking biopsy for definitive diagnosis.

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