Common throughout the world, gastric cancer affects all races. However, unexplained geographic and cultural differences in incidence occur; for example, mortality is high in Japan, Iceland, Chile, and Austria. In the United States, incidence has decreased 50% during the past 25 years, and the death rate from gastric cancer is one-third that of 30 years ago.
The decrease in gastric cancer incidence in the United States has been attributed, without proof, to the balanced American diet and to refrigeration, which reduces the number of nitrate-producing bacteria in food.
Incidence is highest in men over age 40. The prognosis depends on the stage of the disease at the time of diagnosis; overall, the 5-year survival rate is about 15%.
The cause of gastric cancer is unknown. This cancer is commonly associated with gastritis, chronic inflammation of the stomach, gastric ulcers, Helicobacter pylori bacteria, and gastric atrophy. Predisposing factors include environmental influences, such as smoking and high alcohol intake.
Genetic factors have also been implicated because this disease occurs more frequently among people with type A blood than among those with type O; similarly, it’s more common in people with a family history of such cancer.
Dietary factors include types of food preparation, physical properties of some foods, and certain methods of food preservation (especially smoking, pickling, and salting).
According to gross appearance, gastric cancer can be classified as polypoid, ulcerating, ulcerating and infiltrating, or diffuse. The parts of the stomach affected by gastric cancer, listed in order of decreasing frequency, are the pylorus and antrum (50%), the lesser curvature (25%), the cardia (10%), the body of the stomach (10%), and the greater curvature (2% to 3%).
Signs and symptoms
Early clues to gastric cancer are chronic dyspepsia and epigastric discomfort, followed in later stages by weight loss, anorexia, a feeling of fullness after eating, anemia, and fatigue. If the cancer is in the cardia, the first symptom may be dysphagia and, later, vomiting (typically coffee-ground vomitus). Affected patients may also have blood in their stools.
The course of gastric cancer may be insidious or fulminating. The patient typically treats himself with antacids until the symptoms of advanced stages appear.
Diagnosis depends primarily on reinvestigations of persistent or recurring GI changes and complaints. To rule out other conditions that produce similar symptoms, a diagnostic evaluation must include the testing of blood, stools, and stomach fluid specimens.
Gastric cancer commonly requires the following studies for diagnosis: