LAUSR

Background: Abnormal bowel movements have been associated with dyslipidemia, hypertension, diabetes, and altered metabolism of bile acids and gut microbiota, risks factors also associated with hepatocellular carcinoma (HCC). However, little is known about whether bowel movement frequency affects the risk of HCC. Methods: We followed 88,123 women in the Nurses9 Health Study (NHS) and 21,084 men in the Health Professionals Follow-up Study (HPFS). The Cox proportional hazards regression model was used to calculate multivariable hazard ratios (HRs) and confidence intervals (95%CIs). In addition to age, we adjusted for race (white or non-white), gender (female or male), physical activity (lt 3, 3 to 26, ge 27 METS-hours/week), smoking status (never, 1 to 9, ge10 pack-years), alcohol consumption (lt 5, 5 to 14, get 15g/day), aspirin use (yes or no), body mass index (lt 25, 25 to 27.4, 27.5 to 29, ge 30kg/m2), and AHEI-2010 score without alcohol (in quartile) in the multivariable models. Results: We documented 101 incident HCC cases. Compared to those daily bowel movements, participants with bowel movement more than once per day had a multivariable HR of 1.88 (95% CI: 1.15 to 3.09) in the pooled cohorts. The positive association appeared stronger for men (frequent vs. daily, 2.74, 95% CI: 1.15 to 6.49) than for women (frequent vs. daily, 1.57, 95% CI: 0.83 to 2.95) (P-heterogeneity by sex=0.31). We found null associations between infrequent bowel movement and the risk of HCC (HR=1.00, 95%CI: 0.58 to 1.72). The HR (95%CI) for participants who used laxatives regularly relative to those who never used laxatives was 1.03 (0.66 to 1.60). Conclusions: Our results suggest increased bowel movement frequency is associated with a higher risk of HCC. These findings need to be confirmed and potential mechanisms underlying this association need to be elucidated. Citation Format: Lu Long, Xing Liu, Lina Jin, Tracey Simon, Wenjie Ma, Mi Na Kim, Wanshui Yang, Jefferey A. Meyerhardt, Andrew Chan, Edward Giovannucci, Xuehong Zhang. Association of bowel movement frequency and laxative use with risk of hepatocellular carcinoma in US women and men [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 839.