The PDQ editorial boards use a ranking system of levels of evidence to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. For any given therapy, results of prevention and treatment studies can be ranked on each of the following two scales:
Strength of the study design.
Strength of the endpoints.
Together, the two rankings provide a measure of the overall level of evidence. Screening studies are ranked on strength of study design alone...
Management of adenocarcinoma histology, which accounts for 90% to 95% of all gastric malignancies, is discussed in this summary. The site of cancer origin within the stomach has changed in frequency in the United States over recent decades. Cancer of the distal half of the stomach has been decreasing in the United States since the 1930s. However, in the last 2 decades, the incidence of cancer of the cardia and gastroesophageal junction has been rapidly rising. The incidence of this cancer has increased dramatically, especially in patients younger than 40 years.
In the United States, gastric cancer ranks 14th in incidence among the major types of cancer malignancies. While the precise etiology is unknown, acknowledged risk factors for gastric cancer include the following:[3,4,5]
Helicobacter pylori gastric infection.
Diet low in fruits and vegetables.
Diet high in salted, smoked, or preserved foods.
Chronic atrophic gastritis.
Gastric adenomatous polyps.
Family history of gastric cancer.
Menetrier disease (giant hypertrophic gastritis).
Familial adenomatous polyposis.
The prognosis of patients with gastric cancer is related to tumor extent and includes both nodal involvement and direct tumor extension beyond the gastric wall.[6,7] Tumor grade may also provide some prognostic information.
In localized distal gastric cancer, more than 50% of patients can be cured. However, early-stage disease accounts for only 10% to 20% of all cases diagnosed in the United States. The remaining patients present with metastatic disease in either regional or distant sites. The overall survival rate in these patients at 5 years ranges from almost no survival for patients with disseminated disease to almost 50% survival for patients with localized distal gastric cancers confined to resectable regional disease. Even with apparent localized disease, the 5-year survival rate of patients with proximal gastric cancer is only 10% to 15%. Although the treatment of patients with disseminated gastric cancer may result in palliation of symptoms and some prolongation of survival, long remissions are uncommon.