Resistance Training and the Risk of Breast Cancer: A Population-Based Case–Control Study

Background: Convincing evidence supports that moderate to vigorous intensity physical activity decreases the risk of breast cancer. However, less is known about the role specific domains of physical activity play in breast cancer prevention, such as resistance training (RT). This case–control study investigated the association between RT and breast cancer risk. Methods: The Breast Cancer Environment and Employment Study was a population-based case–control study conducted in women aged 18–80 years in Western Australia from 2009 to 2011. Information about demographic, lifestyle, and clinical risk factors of breast cancer was collected via self-administered questionnaire. Participants retrospectively recalled their recreational physical activities for 3 different age periods: 15–24, 25–39, and 40+ years. Data were available from 1149 cases and 1710 controls. Logistic regression was used to examine the relationship between RT and breast cancer risk, after adjusting for a range of confounders. Results: The prevalence of RT ranged from 2% to 11% across the different age periods. Compared with doing none, engaging in RT versus during the age period of 15–24 years was associated with a 52% lower risk of breast cancer (adjusted odds ratio: 0.48; 95% confidence interval, 0.25–0.91). However, no associations were observed for the latter 2 age periods or lifetime RT. Conclusion: These findings provide preliminary evidence that RT in early adulthood may be associated with a lower risk of breast cancer; however, there was no association between RT and breast cancer risk in the older age periods. Further research is required.