The cause of gastric cancer is unknown; however, predisposing factors such as gastritis with gastric atrophy are known to increase the risk. Genetic factors have also been implicated. People with type A blood have a 10% increased risk, and the disease occurs more commonly in people with a family history of such cancer.

Dietary factors related to food preparation and preservation, such as smoked foods, pickled vegetables, and salted fish and meat, may also be implicated. Furthermore, excessive alcohol consumption and smoking increase the risk of developing gastric cancer.

Malnutrition occurs when the stomach can’t digest protein, and GI obstruction develops as the tumor enlarges. Iron deficiency anemia results as the tumor causes ulceration and bleeding. If the patient has pernicious anemia, the tumor can interfere with the production of the intrinsic factor needed for vitamin B₁₂ absorption. As the cancer metastasizes to other structures, additional complications occur.

In the early stages, the patient may complain of pain in his back or in the epigastric or retrosternal areas that’s relieved with nonprescription medications; however, he may not report this symptom because he doesn’t realize its significance. The patient typically reports a vague feeling of fullness, heaviness, and moderate abdominal distention after meals.

Depending on cancer progression, the patient may report weight loss due to appetite disturbance, nausea, and vomiting. He may report coffee-ground vomitus if the tumor is located in the cardia. He may also complain of weakness and fatigue. If the tumor is located in the proximal area of the stomach, he may experience dysphagia.

Palpation of the abdomen may disclose a mass or enlarged lymph nodes, especially the supraclavicular and axillary nodes.
Other assessment findings depend on the extent of the disease and the location of metastasis.