Prospective cohort studies of bowel movement frequency and laxative use and colorectal cancer incidence in US women and men
A partir des données des cohortes américaines "Nurses’ Health Study" incluant 88 173 femmes et "Health Professionals Follow-up Study" incluant 23 722 hommes, cette étude prospective évalue l'association entre la fréquence des selles, l'utilisation de laxatifs et le risque de cancer colorectal
Purpose : The associations between bowel movement frequency, laxative use, and colorectal cancer incidence remain uncertain. No published studies have accounted for potential latency between these factors and colorectal cancer onset. Methods : We prospectively examined these associations among 88,173 women in the Nurses’ Health Study (NHS, 1982–2010) and 23,722 men in the Health Professionals Follow-up Study (HPFS, 2000–2010). Cox proportional hazards regression models were used to estimate multivariable hazard ratios (HRs, 95 % CIs). We conducted time lagged analyses to evaluate the potential latency in the NHS. Results : We documented 2,012 incident colorectal cancer cases. The HRs (95 % CIs) for infrequent bowel movement relative to daily were 0.86 (95 % CI 0.71–1.04) in women and 0.81 (95 % CI 0.48–1.37) in men. The HRs for weekly to daily relative to never laxative use were 0.98 (95 % CI 0.81–1.20) in women and 1.41 (95 % CI 0.96–2.06) in men. In women, the HRs for every 3 days or less bowel movement relative to daily were 0.87 (95 % CI 0.59–1.27) for colorectal cancers that developed within 10 years of assessment, 1.03 (95 % CI 0.85–1.26) for 11–18 years after assessment, and 0.73 (95 % CI 0.54–1.01) for 19–28 years after assessment. The corresponding HRs for weekly to daily relative to never laxative use were 0.93 (95 % CI 0.63–1.37), 1.03 (95 % CI 0.74–1.44), and 0.98 (95 % CI 0.71–1.35), respectively. Conclusion : Bowel movement frequency and laxative use appear not to be associated with colorectal cancer risk in this study.