common in Japan, is the superficial spreading adenocarcinoma that essentially replaces the lining (mucosa) of the stomach with sheets of malignant cells . Another rare subtype is scirrhous carcinoma (linitis plastica), a poorly differentiated mixture of mucin-producing carcinoma cells that infiltrates the muscle wall and turns it into rigid, leatherlike scar tissue that can't stretch or move during the normal digestive process (peristalsis).
Occasionally, a cancer may develop in lymph tissue (gastric lymphoma) or from the smooth muscles of the stomach wall (leiomyosarcoma). Carcinoids and plasmacytomas can also develop in the stomach.
How It Spreads The disease can spread directly through the stomach wall into adjacent organs and through the lymph system to nodes in the abdomen, the left side of the neck and the left armpit. Metastases through the bloodstream can spread to the liver, lungs, bone and brain. Metastases are also found in the lining of the abdominal cavity (peritoneum) and around the rectum.
What Causes It The exact cause is unknown, but most gastric cancers are believed to be caused by carcinogens, with diet as a major factor. Nitrites found in smoked meats, fish and other foods and the nitrates used as food preservatives have been implicated, along with aflatoxin, a carcinogenic fungus contaminant that is present in some foodstuffs such as peanuts.
Various medical conditions are also associated with the development of stomach cancer. A history of or the presence of a Helicobacter pylori infection may lead to stomach inflammation that can induce mutations and
