Objective: The aim of this study was to determine whether bowel movement frequency and laxative use and type were associated with risk of colon cancer in white and black men and women.
Methods: We conducted a population-based, case-control study with equal representation by blacks. Eligible subjects between ages 40 and 80 yr residing in urban and rural communities in North Carolina were asked about bowel habits and laxatives during face-to-face interviews. There were 643 cases (349 white, 294 black) and 1048 controls (611 white, 437 black).
Results: Constipation, defined as fewer than three reported bowel movements per wk, was associated with a greater than two-fold risk of colon cancer (OR 2.36; 95% CI = 1.41-3.93) adjusted for age, race, sex, and relevant confounders. The association was greater for women (OR 2.69; 95% CI = 1.46-4.94) than for men (OR 1.73; 95% CI = 0.61-4.88) and stronger in blacks than whites. Black women had the highest risk (OR 3.42; 95% CI = 1.60-7.34), which remained significant (OR 3.21; 95% CI = 1.46-7.04) even after excluding subjects with late stage (distant) disease. The OR for constipation was slightly higher for distal than for proximal colon cancers. There was no association with laxative use (OR 0.88; 95% CI = 0.69-1.11). Fiber commercial laxatives appeared to exert a protective effect in a small subgroup.
Conclusions: This study provides support for a positive association between constipation and increased risk for colon cancer. Women, especially black women with constipation, seem to be at the highest risk.