Gastric Cancer

Gastric Cancer

The incidence of cancer of the stomach continues to decrease in the United States; however, it still accounts for 12,400 deaths annually (American Cancer Society, 2002). Most of these deaths occur in people older than 40 years of age, but they occasion-ally occur in younger people. Men have a higher incidence of gas-tric cancers than women do. The incidence of gastric cancer is much greater in Japan, which has instituted mass screening pro-grams for earlier diagnosis. Diet appears to be a significant factor. A diet high in smoked foods and low in fruits and vegetables may increase the risk of gastric cancer. Other factors related to the incidence of gastric cancer include chronic inflammation of the stomach, pernicious anemia, achlorhydria, gastric ulcers, H. pylori infection, and genetics. The prognosis is poor, becausemost patients have metastases at the time of diagnosis (Greenlee, 2001).

Pathophysiology

Most gastric cancers are adenocarcinomas and can occur in any portion of the stomach. The tumor infiltrates the surrounding mucosa, penetrating the wall of the stomach and adjacent organs and structures. The liver, pancreas, esophagus, and duodenum are often affected at the time of diagnosis. Metastasis through lymph to the peritoneal cavity occurs later in the disease.

Clinical Manifestations

In the early stages of gastric cancer, symptoms may be absent. Early symptoms are seldom definitive because most gastric tumors begin on the lesser curvature, where they cause little disturbance of gastric functions. Some studies show that early symptoms, such as pain relieved with antacids, resemble those of benign ulcers. Symptoms of progressive disease may include anorexia, dyspepsia (indigestion), weight loss, abdominal pain, constipation, anemia, and nausea and vomiting.

Assessment and Diagnostic Findings

Usually the physical examination is not helpful in detecting cancer because most gastric tumors are not palpable. Ascites may be ap-parent if the cancer cells have metastasized to the liver. Endoscopy for biopsy and cytologic washings is the usual diagnostic study, and a barium x-ray examination of the upper GI tract may also be per-formed. Because metastasis often occurs before warning signs de-velop, a computed tomography (CT) scan, bone scan, and liver scan are valuable in determining the extent of metastasis. A com-plete x-ray examination of the GI tract should be performed when any person older than 40 years of age has had indigestion (dyspep-sia) of more than 4 weeks’ duration.

Medical Management

There is no successful treatment for gastric carcinoma except re-moval of the tumor. If the tumor can be removed while it is still localized to the stomach, the patient can be cured. If the tumor has spread beyond the area that can be excised, cure is impossi-ble. Palliative rather than radical surgery is performed if there is metastasis to other vital organs, such as the liver. In many of these patients, effective palliation to prevent discomfort caused by ob-struction or dysphagia may be obtained by resection of the tumor (see Gastric Surgery).

If a radical subtotal gastrectomy is performed, the stump of the stomach is anastomosed to the jejunum, as in the gastrectomy for ulcer. When a total gastrectomy is performed, GI continuity is restored by means of an anastomosis between the ends of the esophagus and the jejunum.

If surgical treatment does not offer cure, treatment with chemo-therapy may offer further control of the disease or palliation. Commonly used chemotherapeutic medications include cis-platin, irinotecan, or a combination of 5-fluorouracil, doxoru-bicin (Adriamycin), and mitomycin-C. Some studies are being conducted on the use of chemotherapy before surgery. Radiation therapy also may be used for palliation. Assessment of tumor markers (blood analysis for antigens indicative of colon cancer) such as carcinoembryonic antigen, CA 19-9, and CA 50 may help determine the effectiveness of treatment. If these values were ele-vated before treatment, they should decrease if the tumor is re-sponding to the treatment (Bobbio-Pallavicini et al., 2001; Kerby & Heslin, 1999).