RESUMO
[Objective] To compare the influence of first-degree relatives' cancer history on the genetic tendency of gastric and colorectal cancer. [Methods] Patients with gastric and colorectal cancer from six towns of Suzhou City were investigated by means of face-to-face survey based on the "Family History and History of Population Diseases Questionnaire"which included general conditions, family composition and cancer occurrence of all their three degree relatives. [Results] If there were first-degree relatives with history of cancer, individual risk of gastric cancer would be higher than that of colorectal cancer by 55％, with the adjusted OR (95％ CI) being 1.551 (1.021, 2.356). If there were first-degree relatives with history of digestive tract cancer, the risk of the subject would increase to 104％, with the adjusted OR (95％CI) being 2.037 (1.279, 3.246). Men with first-degree relatives who had cancer history was at91％ higher risk of developing gastric cancer than colorectal cancer, with the adjusted OR (95％CI) being1.911 (1.080, 3.381). And for history of digestive tract cancer, the risk would reach 156％, with the adjusted OR (95％ CI) being 2.559 (1.337, 4.897). The number of cancers suffered by first-degree relatives of those patients with gastric cancer was higher than that of patients with colorectal cancer, with Z =-6.873, P<0.001, while the number of digestive tract cancer was also higher, with Z =-6.137, P<0.001. [Conclusion] The history of cancer and digestive tract cancer with first-degree relatives, is more common in patients with gastric cancer than with colorectal cancer. It is necessary to focus health education on men with first-degree relatives suffering from cancer or digestive tract cancer and suggest some changes in their living habits and regular medical examinations to reduce the occurrence of gastric cancer.