Abstract
BACKGROUND: A World Health Organization guideline recommends that adults engage in moderate-to-vigorous physical activity (MVPA). We aimed to clarify associations of total MVPA in any domain with overall and site-specific cancer incidence using Japanese population-based cohort data. METHODS: This study evaluated 84,054 participants (39,053 males and 45,001 females aged 50-79 years) of the 10-year survey of the Japan Public Health Center-based Prospective Study over a median follow-up of 13.0 years. Total MVPA was calculated based on a self-reported physical questionnaire, and 7.5 metabolic equivalent-hours/week (MET-hours/week) was defined as the minimum amount recommended by the guideline. Associations of categorized total MVPA with overall and site-specific cancer incidences were examined using multivariable-adjusted Cox proportional hazard models by sex. RESULTS: Among males, the risk reduction was non-significant even in the highest MVPA category compared with no total MVPA. Among females, in contrast, risk of total cancer was reduced even when they engaged in lower total MVPA than the recommended amount (0.1-7.4 MET-hours/week) compared with no total MVPA (hazard ratio 0.79; 95% confidence interval, 0.65-0.97), and no further risk reduction was observed with increasing MVPA. Regarding site-specific cancers, engaging in higher total MVPA was inversely associated with risks of colon cancer (males) and bladder and endometrial cancers (females). CONCLUSION: Total MVPA was associated with reduced risk of overall cancer incidence in females, but not in males.