Bowel movement, use of laxatives and risk of colorectal adenomatous polypsamong women (United States)

Background: Infrequent bowel movements and use of laxatives have been hypot hesized to increase risk of colorectal neoplasia. However, the few existing epidemiologic studies in humans have been inconclusive. Purpose: To investigate prospectively the associations of bowel movement fr equency and laxative use with the occurrence of adenomatous colorectal poly ps in women. Methods: A total of 17,400 women 36-61 years of age, without previous diagn osis of cancer or polyps, responded to a mailed questionnaire in 1982 that assessed bowel movement frequency and use of laxatives and had an endoscopy between 1984 and 1996. Between 1984 and 1996, 906 cases of adenomatous pol yps (496 classified as small (<1 cm), 358 classified as large (greater than or equal to1 cm) and 52 unclassified) were documented. Relative risks (RRs ) of adenomas and 95% confidence intervals (CIs) were calculated using logi stic regression. Results: After controlling for adenoma risk factors, the multivariate RRs a ssociated with having bowel movements every third day or less compared to o nce daily were 0.9 (95% CI: 0.7-1.2) for total colorectal adenomas, 1.0 (95 % CI: 0.7-1.5) for large adenomas and 1.0 (95% CI: 0.7-1.3) for adenomas of the colon only. The multivariate RRs associated with weekly to daily laxat ive use compared to never use were 0.9 (95% CI: 0.7-1.1) for total colorect al adenomatous polyps, 1.0 (95% CI: 0.7-1.5) for large adenomas and 0.8 (95 % CI: 0.6-1.2) for colon adenomatous polyps only. Conclusion: These findings do not support an association between infrequent bowel movement or laxative use and risk of colorectal adenomas.