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| Adenocarcinoma of Stomach | ||
| Etiology •Dietary factors associated with gastric carcinoma are increased: salted fish and meat, pickled vegetables, starch, smoked foods, and nitrates in drinking water or foods •Protective dietary factors are: fresh vegetables, citrus fruits, vitamin C •Genetic factors associated with increased risk are: Blood group A; some familial cancer syndrome kindreds (Lynch Type II); a first degree relative with gastric cancer; and familial polyposis •Any condition causing chronic gastritis such as H.pylori infection; atrophic gastritis •Relative alkalinization of the gastric contents including atrophic gastritis, and duodenal reflux •Miscellaneous factors include smoking and Menetrier's disease | ||
| Pathogenesis •A unified theory of pathogenesis is not yet possible for gastric cancer, although evidence exists for the role of nitroso compounds in the formation of many gastric cancers •The dietary factors involved often are associated with increased intake of nitrates or nitrites, or a decrease in reducing agents which prevent the formation of nitrites from nitrates •The common pathways of gastric atrophy, intestinal metaplasia and hypochlorhydria favor the introduction of nitrite forming bacteria in the stomach •Nitroso compounds formed from nitrites have been strongly implicated as carcinogens, | ||
| Epidemiology •Marked geographic variation from a high of 66.9/100,000 population in Costa Rica to <6/100,000 in the U.S •Other high incidence areas are: Japan and the former Soviet Union •The incidence of distal gastric cancer has decreased dramatically in this country, representing a decrease in the intestinal type of gastric carcinoma, while there has been a rise in proximal gastric carcinoma •Gastric carcinoma occurs primarily after age 50 •There is a 2/1 male predominance for the intestinal type, with an equal male/female for the mucus secreting type | ||
| General Gross Description •Gastric carcinoma is most frequent in the antrum (60%) followed by cardia (25%) and body •The gross appearance of gastric carcinomahas been subdivided as follows: fungating (36%) is exophytic with large surface ulcerations, and irregular margin measuring several centimeters in diameter; infiltrative (26%) is flat generally without ulceration and may involve the full thickness of the gastric wall. 1/3 of these tumors involve the entire stomach producing a stiffened gastric wall called linitis plastica: ulcerated (25%) is not exophytic and is composed predominantly of an ulcer, with raised stiff margins of infiltrating tumor; polypoid (7%) is an exophytic mass with well defined margins and without ulcerations; superficial spreading (6%) is usually flat, with superficial involvement of the gastric wall and without ulceration •Some gastric carcinomas have well defined infiltrating margins and others such as the diffusely infiltrating type advance as single cells or small clusters of cells whose gross extent is impossible to define •Gastric carcinomas of the mucus producing type may have pools of grossly visible translucent mucin •Tumors of the cardia and pylorus can extend submucosally into the esophagus and duodenum respectively •The primary extragastric spread is through regional lymph nodes and differs for proximal and distal gastric tumors •Examples: | ||
| General Microscopic Description •Histologically, gastric carcinoma has been classified into the intestinal and diffuse type •The intestinal type forms glands resembling colonic carcinoma •The diffuse type contains gastric mucus cells which when filled with mucus may have an eccentrically compressed peripheral nucleus forming a "signet ring" cell. •The diffuse type does not form glands but infiltrates as single cells or small clusters of cells often with a marked desmoplastic reaction leading to the linitis plastica appearance of the gastric wall seen in diffusely infiltrating tumors •Some tumors may have combined features of both intestinal and diffuse type •Examples: | ||
| Clinical Correlation •Gastric cancer is symptomatic late in its course when abdominal pain and weight loss are noted •Distal tumors late in their course may present with signs of obstruction •Grossly evident bleeding either hematemesis or melena are infrequent •These tumors may present with metastasis to Virchow's node (left supraclavicular), ovary (Krukenberg tumor), liver or peritoneum •Laboratory findings are usually not helpful in making the diagnosis •The diagnosis is usually made following endoscopy with biopsy, sometimes with a preceding upper GI series •Standard therapy for attempted cure is radical surgery •Radiotherapy or chemotherapy have not yet been shown to increase the disease free interval •Cure rates are dependent on the stage of disease when diagnosed and are better in countries like Japan where aggressive screening of individuals at risk results in diagnosis of early asymptomatic disease •The five year survival for localized distal disease is 50%, whereas the 5 yr. survival for localized proximal disease is only 10-15% | ||
| References •CancerNet from the NCI 5/97 •Robbins Pathologic Basis of Disease 5th ed., Cotran RS et al., WB Saunders Philadelphia 1994 pp779-783 Please be patient during transfer. Medline will open in a new window. To return, close the Medline Window Adenocarcinoma of Stomach
| Synopsis by: Martin Nadel, M.D. (T63000M81403)[410]
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