A 72-year-old Japanese immigrant was brought in by his family with complaints of difficulty in eating, vague abdominal pain, and weight loss. Endoscopy and biopsy confirmed gastric adenocarcinoma (Figure 60-1). Liver metastases were found on abdominal CT. The family and the patient chose only comfort measures and the patient died 6 months later.
Endoscopy showing a raised and irregular mass in the antrum of the stomach deforming the pylorus. It fills the distal one-half of the antrum. The lesion was hard when probed with biopsy forceps. Biopsy indicated adenocarcinoma. (Courtesy of Michael Harper, MD.)
Gastric cancer is a malignant neoplasm of the stomach, usually adenocarcinoma.
- Based on Surveillance Epidemiology and End Results (SEER) data, an estimated 12,730 men and 8270 women will be diagnosed with gastric cancer, and 10,570 men and women will die of this cancer in 2012 (2010).1 The median age at diagnosis is 70 years and median age at death from gastric cancer is 73 years.1
- Stomach cancer occurs in 10.8 per 100,000 men and 5.4 per 100,000 women in a year. In 2008, the United States prevalence was 37,739 men and 28,271 women, with a lifetime risk of 0.88%.1
- High rates of stomach cancer occur in Japan, China, Chile, and Ireland.2
- Eighty-five percent of stomach cancers are adenocarcinomas with 15% lymphomas and GI stromal tumors.2 Adenocarcinoma is further divided into two types:
- Diffuse type—Characterized by absent cell cohesion, these tumors affect younger individuals infiltrating and thickening the stomach wall; the prognosis is poor. Several susceptibility genes have been identified for this type of cancer.3
- Intestinal type—Characterized by adhesive cells forming tubular structures, these tumors frequently ulcerate.
- Tumor grade can be well (4.1%), moderate (23.1%), or poorly differentiated (54.9%), or undifferentiated (2.9%) (SEER data from 1988-2001; unknown type accounted for 15%).4
- Most tumors are thought to arise from ingestion of nitrates that are converted by bacteria to carcinogens. Exogenous and endogenous factors (see “Risk Factors” below) contribute to this process.2
- Exogenous sources of nitrates—Sources include foods that are dried, smoked, and salted. Helicobacter pylori infection may contribute to carcinogenicity by creating gastritis, loss of acidity, and bacterial growth.
- Oncogenic pathways identified in most gastric cancers are the proliferation/stem cell, nuclear factor-κB, and Wnt/β-catenin; interactions between them appear to influence disease behavior and patient survival.5
- Gastric tumors are classified for staging using the T (tumor) N (nodal involvement) M (metastases) system. Two important prognostic factors are depth of invasion through the gastric wall (less than T2 [tumor invades muscularis propria]) and presence or absence of regional lymph node involvement (N0). Changes made to the classification system in the seventh edition of the American Joint Commission's Cancer Staging Manual for gastric cancer6 demonstrate better survival discrimination.7
- Gastric cancer spreads in multiple ways:2...