Gastric Cancer
(N Engl J Med 1995;333:32-41)
DEFINITION:
Cancer of the stomach; Adenocarcinoma is classified, via Lauren in 1965, into:
Intestinal variant: arise from gastric mucus cells that have undergone intestinal metaplasia in setting of chronic gastritis
Microscopically resembles colonic adenocarcinoma; may be polypoid or ulcerated or both
Better differentiated; becoming less prevalent in the U.S.
Risk factors: Diet (nitrates, smoked foods, ↓ vegetable/fruits), H. Pylori, Pernicious anemia (Type A gastritis), Billroth I & II
Diffuse variant: arise directly from native gastric mucus cells, is not associated with chronic gastritis
Poorly differentiated and infiltrating; accounts for half of all gastric cancers in U.S.; Poorer prognosis
Risk factors: H. Pylori,? association with blood group A
Can infiltrate the stomach extensively given thickened appearance: Linitis Plastica (“leather bottle stomach”)
EPIDEMIOLOGY:
World wide: second most common cancer with 750,000 new cases per year; Second most deadly cancer behind lung cancer
In U.S.: 22,000 new cases per year, 8th most deadly cancer for men, 10th for women; Incidence increases dramatically >50 yrs old
Over 80% are adenocarcinomas
Less common: gastric lymphomas, gastric stromal tumors, leiomyosarcomas, carcinoid, metastatic (i.e. melanoma, breast)
Mucosal Associated Lymphoid Tumors (MALT): often low grade B-cell lymphomas (non-Hodgkin’s), but may be high grade aggressive tumors
Cause: association (90%) with infection by H. Pylori (seems to drive lymphoid proliferation in the lamina propria and tumor development)
Gastric Lymphoma (non-MALT)
Primary gastric lymphoma is rare and accounts for less than 5% of gastric malignancies
Immunoperoxidase staining or lymphoma markers increase diagnostic accuracy
Non-Hodgkin’s is much more common than Hodgkin’s lymphoma
Gastric Carcinoid (neuroendocrine cell growths): benign or malignant, stain for chromogranin; See also Bowel- Carcinoid Tumors (Chapter 2.08)
Cause: de novo malignant transformation or loss of normal growth regulation in response to chronic elevation of serum gastrin levels
Gastritis Type A (Pernicious anemia) has gastric cancer incidence of 2-10% (i.e. elevation in serum gastrin levels) See also Esophagus/Gastric- Gastropathy (Chapter 1.13)
There is a risk of gastric cancer in the gastric remnant after gastrectomy (Gastric stump carcinoma): 2-4 fold increase 15 years after surgeryRelated posts:
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