A Case-Control Study on dietary Factors of Colorectal Adenomatous Polyps by Sites

Kim, Mi Kyung; Lee, Won Chul; Choi, Kyu Yong; Kim, Su Kil; Lee, Se Young; Lee-Kim, Yang Cha; Meng, Kwang Ho

Abstract

Colorectal adenomas are benign neoplasm in the large bowel that are thought to be precursors lesion to colorectal cancer. So, studying adenomatous polyps instead of cancer might allow one to measure the diet of relatively asymptomatic subjects closer to the time of the initial neoplastic process. Some dietary factor, or set of factors, apparently plays an impotant role in the etiology of colorectal adenomatous polyps. The difference of the possible association of colorectal adenomatous polyps with dietary risk factors by anatomic subsite and gender was investigated in this case-control study. Between July 1994 and April 1998, 314 cases of patients with pathologically confirmed incident colorectal adenomatous polyps and 88 control subjects were collected from Our Lady of Mercy Hospital, The Catholic University. After colonoscopy, infor-mation on exposure was obtained by the interviewers. Also, subjects were interviewed using the semiquantitative food frequency questionnaire, and average daily nutrient intakes were calculated. Site- and gender-specific odds ratio relative to the lowest tertile of intake for each nutrient were determined using unconditional logistic regression after adjusting for a number of potential confounders. In females, significant odds ratio were found for b-carotene(0.31, 95% CI, 0.10~0.95), vitamin C(0.11, 95% CI, 0.02~0.61), vitamin-E(0.11, 95% CI, 0.02~0.78) in right colon but only the odds ratio of vitamin E(0.17, 95% CI, 0.03~0.90) was statistically significant in left colon. Among food groups, the odds ratio of green yellow vegetables was significant(OR=0.21, 95% CI, 0.05~0.96) in right colon. In males, almost all the above dietary factors were statistically not significant. In males, cigarette smoking appears to be a signigicant risk factor(OR=8.86, 95% CI, 1.10~71.5) in left colon, it was statistically not signigicant(OR=1.63, 95% CI, 0.42~4.76) in the right colon. Findings fron this study show that many associations of the nutrients with colorectal adenomatous polyps risk are different by anatomic subsite and gender and support the hypothesis that high intake of antioxidant vitamins and green yellow vagetables decreases the risk of polyps.