Gastric cancer risk factors: a case-control study based on medical records.

Four hundred and sixty gastric cancer patients who had undergone operation at the National Cancer Center Hospital and an equal number of age-matched controls were analyzed in order to estimate the influence of gastric cancer family inheritance and cigarette smoking habit. Relative risks for cigarette smoking habit, for gastric cancer family inheritance and for both were 2.88, 1.67 and 4.12, respectively. Earlier age of onset of gastric cancer was observed in the gastric cancer cases with both risk factors as compared with the other patients.