[Comparison between large bowel cancer in young people and that in middle-aged and old-aged people]

In order to understand the difference in risk factors of large bowel cancer in different age groups, a population-based case-control study including two age groups, one group with the age of < or = 40 (180 cases and 184 controls). And the other group with the age of > 40 (1148 cases and 1161 controls), was conducted in Shanghai. The study indicated that: 1. The patients of age > 40 with large bowel cancer had closer relationship with the environmental factors (esp. dietary and nutritional factors) than the patients of age < or = 40. 2. The familial genetic risk factor which affected development of the cancer in younger group was two-fold higher than that in elder group. The results suggested that both genetic and environmental factors influenced the occurrence of the cancer, and the role of the genetic factor in < or = 40-yr group and that of the environmental factors in > 40-yr group appeared to be important.