Total moderate-to-vigorous physical activity across the adult life course and the risk of invasive ovarian cancer

BACKGROUND: Previous research on moderate-to-vigorous physical activity (MVPA) and ovarian cancer risk have shown inconsistent results. Most studies measured recreational MVPA once during late adulthood, which does not consider the way in which timing may differently influence risk or account for MVPA from other activities. Life-course epidemiology models (critical-period, sensitive-period, and accumulation) can evaluate whether the timing and cumulative burden of total MVPA across the lifespan influences risk. Here, we identify which model best describes the association between total MVPA, encompassing recreational, occupational, household, and transportation activities, and invasive ovarian cancer risk. METHODS: A population-based case-control study of ovarian cancer in Montreal, Canada (2011-16) included 268 invasive cases and 668 controls aged ≥52 years. Total MVPA was determined by using recalled information on the frequency and duration of various physical activities across adulthood. A Bayesian relevant life course exposure model was used to estimate the relative importance of total MVPA, represented as average energy expenditure in units of metabolic equivalent (MET)-hours/week, during three pre-specified periods (early reproductive years, late reproductive years/perimenopause, and postmenopause) on invasive ovarian cancer risk. RESULTS: The lifetime-effect odds ratio comparing ≥50 vs