Plant foods and differences between colon and rectal cancers

A case-control study on plant food intake and its role in the risk of colon and rectal cancers was carried out in Montevideo, Uruguay. Four hundred and eighty-four (484) cases of colorectal cancer and 1452 controls were frequency matched on age, sex, residence and urban/rural status. Among cases, 260 patients had colon cancer whereas 224 had rectal tumours. Controls had non-neoplastic conditions. Both cases and controls were interviewed in the four major hospitals in Montevideo shortly after admittance for diagnosis or treatment. The questionnaire included a section on frequency of foods, which included 64 items, in particular, queries on 18 vegetables, 10 fruits and 6 cereal dishes were included. Thus, the amount of plant foods consumed was complete and included the main plant foods in the Uruguayan diet. The analysis showed that rectal cancer displayed inverse associations with total plant foods, total vegetables, cooked vegetables, potatoes and legumes. When data were stratified by tumour site and sex, only men showed a protective effect of plant foods (odds ratio (OR) of rectal cancer for men 0.4, 95% confidence interval (CI) 0.2-0.7). In contrast, women with rectal carcinoma were not associated with plant food intake. It can be concluded that plant foods are protective factors for men afflicted with colorectal cancer but that plant food intake is not associated with risk in women. This is, at least in part, due to the high risk associated with bread intake in this gender.