Abstract
Mounting evidence indicates a potential beneficial effect of vigorous-intensity physical activity on hepatocellular carcinoma (HCC). However, the association between moderate-intensity physical activity, such as brisk walking, and the risk of HCC remains largely unknown. Two prospective cohorts of 77,535 women from the Nurses' Health Study and 44,540 men from the Health Professionals Follow-up Study were included. Weekly time spent on physical activities were updated biennially. The Cox proportional hazard regression model was used to calculate multivariable hazard ratios (HR) and 95% confidence intervals (95% CI). After an average 23-year follow-up, we identified 138 incident HCC cases. A higher amount of total physical activity was not significantly associated with a reduced risk of HCC (top tertile vs. bottom tertile; HR = 0.78; 95% CI, 0.51-1.18; P (trend) = 0.33). For the same comparison, there was an inverse association between moderate-intensity activity and HCC risk (HR = 0.60; 95% CI, 0.38-0.94; P (trend) = 0.04), whereas no statistically significant association with vigorous-intensity activity (HR = 0.88; 95% CI, 0.56-1.37; P (trend) = 0.74). Engaging in brisk walking was significantly associated with a lower risk of HCC (over 1 hour/week vs. non-brisk walking; HR = 0.50; 95% CI, 0.31-0.78; P (trend) = 0.006). The association between brisk walking and HCC risk was generally present across all subgroups, including age, body mass index, type 2 diabetes mellitus, smoking status, aspirin use, and alcohol consumption (all P (interaction) ≥ 0.05). In conclusion, moderate-intensity activity, especially brisk walking, was associated with reduced risk of HCC among U.S. men and women. If confirmed, brisk walking might serve a feasible way for HCC prevention.