ASPO Abstracts

Physical activity from adolescence through midlife and associations with obesity and endometrial cancer risk

Authors: Saint-Maurice PF, Sampson JN, Michels KA, Moore SC, Loftfield E, McClain K, Cook MB, Trabert B, Matthews CE

Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2021

Abstract Body:
PURPOSE: This study sought to describe the physical activity-endometrial cancer association and potential mediation of this relationship by obesity in midlife. METHODS: Participants were 67,705 women (aged 50–71 years) enrolled in the NIH-AARP cohort who reported their historical leisure-time physical activity patterns starting at age 15–18 years. We identified five long-term physical activity patterns between adolescence and cohort entry (i.e., inactive, maintained-low, maintained-high, increasers, decreasers). We used Cox regression (Hazard ratio - HR [95% CI]) to assess the relationship between these patterns and midlife obesity and endometrial cancer, adjusting for covariates. Mediation analysis was used to decompose the physical activity patterns-endometrial cancer association to estimate the proportion of the physical activity-endometrial cancer association mediated by midlife obesity. RESULTS: During an average 12.3 years of follow-up 1,468 endometrial cancers occurred. Long-term physical activity patterns were inactive, maintained-low, maintained-high, increasers, and decreasers. Compared to long- term inactive women, women who maintained-high or increased activity levels had a 19–26% lower risk for endometrial cancer (maintained-high: HR=0.81 [0.67, 0.98]; increasers: HR=0.74 [0.61, 0.91]). They also had a 45–77% lower risk for obesity in midlife (e.g., maintained-high, BMI 30-39.9: HR=0.50 [0.46, 0.55]; maintained- high, BMI 40+: HR=0.32 [0.26, 0.39]). Obesity was a significant mediator and appeared to account for 55-63% of the physical activity-endometrial cancer associations observed. CONCLUSIONS: Both initiating and maintaining physical activity throughout adulthood can play a role in preventing obesity and in turn, lowering the risk for endometrial cancer.

Keywords: leisure-time physical activity; BMI; mediation