[Comparison of risk factors between left and right-sided colon cancer]

To compare differences of risk factors between left-sided and right-sided colon cancer, a population-based comparative case-control study involving 267 patients with left colon cancer, 247 with right colon cancer and 1451 population controls matched by age (+/- 5 yrs) and sex was carried out in Shanghai. The major causes in the two cancer groups were dietary and nutritional factors. Vegetables, ascorbic acid, riboflavin, tocopherol and carotenes played a protective role in the two groups, but various other foods and some vitamins displayed different relations with the two types of cancer. A negative association was observed between dietary fiber and right colon cancer. Animal fat and some fatty acids (e.g. saturated fatty acids, mono-unsaturated fatty acids and oleic acid) significantly elevated the risk for left colon cancer, but only slightly for right colon cancer. Physical activity and familial history of colorectal cancer in first degree relatives showed a more remarkable relationship with left- than right-sided colon cancers.