Baumeister SE, et al. - By performing a systematic review and meta-analysis, researchers examined the link between physical activity and liver cancer risk by analyzing data from 14 prospective studies (including 6,440 liver cancers). They used a random-effects model to calculate mean HRs and 95% CIs. The mean HR for high vs low physical activity was estimated to be 0.75. Findings revealed an inverse link of physical activity with the risk of liver cancer. In the bias analysis, the investigators found that an unobserved confounder would have to be related to a 1.99-fold rise in the risk of physical activity or liver cancer to explain away the observed mean HR.