Gastric Cancer

The body is made up of many types of cells. Normally, cells grow, divide and die. Sometimes, cells mutate (change) and begin to grow and divide more quickly than normal cells. Rather than dying, these abnormal cells clump together to form tumors. If these tumors are cancerous (also called "malignant"), they can invade and kill your body's healthy tissues.

Gastric cancer (also called "stomach cancer") is the growth of cancer cells in the lining and wall of the stomach.

Although gastric cancer is common throughout the world in people of all races, its incidence exhibits unexplained geographic, cultural, and gender differences.For example, mortality from this disorder is high in Japan, Iceland, Chile, and Austria. Incidence is also higher in men over age 40.

Over the past 25 years in the United States, the incidence of gastric cancer has decreased 50%, with the resulting death rate now one-third of what it was 30 years ago. This decrease has been attributed, without proof, to the improved, well-balanced diets most Americans enjoy and to refrigeration, which reduces the number of nitrate-producing bacteria.

Gastric cancer occurs more commonly in some parts of the stomach than in others; the pyloric area accounts for 50% and the lesser curvature for 25% of the incidence. This adenocarcinoma rapidly infiltrates the regional lymph nodes, omentum, liver, and lungs by way of the walls of the stomach, duodenum, and esophagus; the lymphatic system; adjacent organs; the bloodstream; and the peritoneal cavity.

Causes

Gastric cancer is a major cause of cancer death worldwide, especially in developing countries. Although infection with Helicobacter pylori bacteria may be a risk factor, the exact cause of stomach cancer is unknown. Certain populations appear to be at higher risk, with the incidence of gastric cancer highest in Central Europe, South America, and Asia, especially Japan. Yet over the past several decades, the frequency and mortality associated with gastric cancer have decreased significantly in the United States. For example, since 1930, the incidence has declined about fourfold to about seven cases for every 100,000 people. The reasons for this decline are unknown, but it has been proposed that it may be related to changes in diet and improved food storage.

Signs and Symptoms

Stomach cancer has few symptoms in the early stages. As it progresses, symptoms may include nausea, indigestion or stomach pain, diarrhea or constipation, bloody stools, vomiting blood, loss of appetite, weight loss, anemia, and feelings of fullness or pressure in the stomach.

Diagnostic tests 

Barium X-rays of the GI tract with fluoroscopy show changes that suggest gastric cancer. Changes include a tumor or filling defect in the outline of the stomach, loss of flexibility and distensibility, and abnormal gastric mucosa with or without ulceration.

Gastroscopy with fiberoptic endoscope is used to help rule out other diffuse gastric mucosal abnormalities by allowing direct visualization. Gastroscopic biopsy permits evaluation of gastric mucosal lesions. Photography during gastroscopy provides a permanent record of gastric lesions that can later be used to judge disease progression and the effectiveness of treatment.

Gastric acid stimulation test discloses whether the stomach secretes acid properly.

Blood studies are used to monitor the course of the disease, complications, and the effectiveness of treatment. These studies include a complete blood count, chemistry profiles, arterial blood gas analysis, liver function studies, and a carcinoembryonic antigen radioimmunoassay.

Certain other studies may rule out specific organ metastases. These include computed tomography scans, chest X-rays, liver and bone scans, and liver biopsy.

Treatment

Surgery to remove the tumor often is the treatment of choice. Excision of the lesion with appropriate margins is possible in more than one-third of patients. Even in a patient whose disease isn't considered surgically curable, resection eases symptoms and improves the potential benefits of the chemotherapy and radiation therapy that usually follow surgery.

The nature and extent of the lesion determine the type of surgery. Surgical procedures include gastroduodenostomy, gastrojejunostomy, partial gastric resection, and total gastrectomy. If metastasis has occurred, the omentum and spleen may have to be removed.

Chemotherapy for GI tumors may help control signs and symptoms and prolong survival. Gastric adenocarcinomas respond to several agents, including fluorouracil, carmustine, doxorubicin, and mitomycin. Antiemetics can control nausea, which intensifies as the tumor grows. In the more advanced stages, the patient may need sedatives and tranquilizers to control overwhelming anxiety. Opioid analgesics can relieve severe and unremitting pain.

If the patient has a nonresectable or partially resectable tumor, radiation therapy is effective if combined with chemotherapy. The patient should receive this therapy on an empty stomach but not preoperatively because it may damage viscera and impede healing.

Treatment with antispasmodics and antacids may help relieve GI distress.

Prevention

In Japan, where the risk of gastric cancer is very high, mass screening programs have been successful in detecting disease in the early stages. The value of screening in the US and other countries with lower rates of gastric cancer is not clear. Avoiding smoking may reduce risk.