Risk factors of stomach cancer include stomach polyps, smoking, pernicious anemia, chronic stomach inflammation and a Helicobacter pylori infection, explains Mayo Clinic. Having a diet high in salty foods or low in fruits and vegetables; consuming foods polluted with aflatoxin fungus; and having a family history of stomach cancer are other risk factors of the disease.
Researchers are unsure of what causes stomach cancer. There appears to be a strong correlation between people whose diets consist of many pickled, salted and smoked foods and the incidence of acquiring the disease, notes Mayo Clinic. Determined by the cells that form the cancer, the type of cancer affects the treatment options available.
Adenocarcinoma, the most common form of stomach cancer, starts in the glandular cells as they emit a layer of mucus to protect the stomach's lining from acidic digestive juices, according to Mayo Clinic. Typically, this is the form of cancer people refer to when discussing stomach cancer. Another type of stomach cancer, lymphoma, is extremely rare and originates in the immune system cells. It forms when the small amount of immune system cells in the stomach walls form cancer. Cells that produce hormones can lead to carcinoid cancer. A gastrointestinal stromal tumor begins in the nervous system tissues and is an unusual form of stomach cancer.