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Gastric Cancer: Overview and Risk Factors

Gastric cancer is the second most common malignancy worldwide and the 11th most common in the United States. Prevalence has been decreasing over the last century, likely due to better methods of food preservation. In addition, improved screening techniques-especially in Japan and other high-risk areas-have led to a decrease in mortality. Nonetheless, gastric cancer remains one of the most lethal malignancies, with the 5-year survival rate in the United States less than 20%.

More than 90% of cases are adenocarcinomas, which are derived from glandular tissue. The two general tumor types are intestinal and diffuse. In the intestinal type, which is more common, the tumors grow as discrete masses and eventually erode through the stomach wall into nearby organs. The diffuse type is less common overall, but is more prevalent in younger patients and carries a poorer prognosis. Diffuse tumors are poorly differentiated cancers with little cell cohesion. As a result, they grow outward along the submucosa of the stomach, widely enveloping the stomach without producing a discrete mass.

Tumors tend to be asymptomatic until the disease is advanced. The most common symptoms of advanced tumors are weight loss, early satiety, abdominal pain, nausea, and vomiting. Among the less common symptoms are dysphagia, melena, a palpable abdominal mass, and ascites.

Risk Factors

Incidence varies greatly by geographic area and race. Areas of highest incidence include Japan, Chile, and parts of Eastern Europe. African Americans, Asian Americans, and Latinos have a higher incidence than other demographic groups in the United States. Other risk factors are:

H. pylori infection. Chronic infection is a strong risk factor for gastric cancer of the distal stomach and may be responsible for up to 90% of distal gastric cancers.

Chronic gastritis, pernicious anemia, partial gastrectomy. A history of any of these conditions increases gastric cancer risk.

Genetics. A positive family history and blood type A are associated with an increased risk. The roles of specific genes are still unclear.

Gender. Males have twice the risk of females.

Diet. Factors strongly associated with an increased risk include high intake of salted, smoked, and pickled foods, and low intake of fruits and vegetables. (See Nutritional Considerations.)

Alcohol and tobacco use. Although both alcohol and tobacco use have long been considered risk factors, no conclusive evidence for their roles in gastric cancer has been demonstrated.

Age. The disease is rare before age 40, and the incidence increases steadily thereafter.

 

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Gastric Cancer: Diagnosis and Treatment >>