Food items and food groups as risk factors in a case-control study of diet and colo-rectal cancer.

The contributions of food items and food groups as risk factors in a previously reported case-control study of diet and colo-rectal cancer have been analyzed. The study included 348 patients with colon cancer, 194 with rectal cancer, 542 neighbourhood controls individually matched to the cases on the basis of age and sex and a second control series of 535 surgical hospital controls frequency matched to the cases. For colon cancer, as in the previous analysis, the major risk factor was saturated fat, individual food items or groups failing to make a significant contribution to the risk. In particular there was no protective effect of dietary fibre and, for cruciferous vegetables, only a minor protective effect in females. No individual cruciferous vegetable made an important contribution to this effect. For rectal cancer, on the other hand, a significant effect of saturated fat, independent of other food items or groups, was only found for females in the highest consumption category. For males, consumption of eggs, beef and veal significantly increased risk but not consumption of pork, while for females, there was a non-significant increase in risk with consumption of eggs, no increased risk with consumption of beef or veal and a significantly increased risk with consumption of pork. There was no protective effect of dietary fibre or of cruciferous vegetables for rectal cancer, but in females, there was a significantly increased risk for consumption of beer, though this was somewhat reduced when controlled for consumption of saturated fat. There was no indication of an effect of alcohol in either sex or of beer in males. Thus, these results confirm the previous report in showing a significant effect of saturated fat in increasing risk of colon cancer but suggest a contribution of meats to risk of rectal cancer.