Cancer
Domain-specific physical activity across the life course on the risk of ovarian cancer Jennifer Ritonja* Jennifer Ritonja Sreenath Madathil Belinda Nicolau Lisa Leung Vikki Ho Michal Abrahamowicz Anita Koushik
Past studies examining moderate-to-vigorous physical activity (MVPA) and ovarian cancer risk have focused on recreational MVPA and have found inconsistent results. Most studies measured MVPA during older adulthood, which may not represent pertinent exposure. To-date, no study has examined how timing of MVPA across the lifetime from all four primary domains (recreation, occupation, housework and transportation) impacts risk. Using the life course approach, we sought to identify if ovarian cancer risk is influenced by total (from all four sources) and domain-specific MVPA during certain critical or sensitive life periods or accumulated over adulthood. In a population-based case-control study in Montreal (2011-2016), MVPA was determined using recalled information on the frequency and duration across adulthood of physical activities from all domains. We used the Bayesian relevant life course exposure model to estimate the relative importance of MVPA exposure during 3 life periods (early childbearing years [ages 20-29], late childbearing years/perimenopause [ages 30-49], and postmenopause [ages ≥50]) on ovarian cancer risk. In preliminary results among 344 cases and 668 controls aged ≥52 years, the domain with the largest contribution to total MVPA was housework (between 65-70% for the 3 life periods). Increasing cumulative exposure to MVPA across the adult life course was associated with a reduced ovarian cancer risk for both total and housework MVPA, with ORs for each additional 50 metabolic equivalent (MET)-hours/week of: OR=0.91; 95% credible interval (CrI)=0.78-1.04 for total MPVA, and OR=0.85; 95% CrI=0.67-1.02 for housework MVPA. For both, the posterior distributions for importance of the three life periods were similar. ORs for other physical activity domains did not support a reduced risk. Our findings support the life course hypothesis of an accumulation effect in the association between MVPA and ovarian cancer risk, mainly driven by housework MVPA.