Diet and vitamin or mineral supplementation and risk of rectal cancer in Canada

The study examines the relation of diet and vitamin or mineral supplementation with risk of rectal cancer. Mailed questionnaires were completed by 1 380 newly diagnosed patients with histologically confirmed rectal cancer and 3 097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socioeconomic status, lifestyle, diet and vitamin or mineral supplementation. We derived odds ratios and 95% confidence intervals through unconditional logistic regression. Total of consumption of vegetables, fruit and whole-grain products did not reduce the risk of rectal cancer. Consumption of cruciferous vegetables was inversely associated with risk of rectal cancer among women only, as did chicken intake among men. The strongest dietary association with increased rectal cancer risk appeared in males with increasing total fat intake and in females with bacon intake. Vitamin and mineral supplementation showed significant inverse associations with rectal cancer in women only. These findings suggest that dietary risk factors for rectal cancer in women may differ from those in men.