Bowel movement, state of stool, and subsequent risk for colorectal cancer: The Japan public health center-based prospective study

PURPOSE: Evidence about whether irregular bowel movements or unusual stool conditions are associated with colorectal cancer is still inconsistent. METHODS: We identified 479 newly diagnosed cases of colorectal cancer (303 men and 176 women) during a 7.9-year follow-up of a cohort consisting of 57,940 subjects (27,529 men and 30,411 women) aged 40 to 69 years at baseline. Bowel movements and stool conditions were asked through a self-administered questionnaire. RESULTS: Neither high nor low frequency of bowel movements was associated with colorectal cancer incidence compared with one bowel movement per day. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for two bowel movements or more per day were 1.03 (95% Cl, 0.76-1.41) in men and 1.16 (95% Cl, 0.68-2.00) in women. HRs for two to three bowel movements per week were 0.97 (95% Cl, 0.61-1.55) in men and 0.75 (95% Cl, 0.49-1.13) in women. There was no clear association between an unusual stool state, such as diarrhea or hard stools, and colorectal cancer. CONCLUSION: Our results suggest that neither bowel movement frequency nor any specific state of stool causes colorectal cancer. (c) 2006 Elsevier Inc. All rights reserved.