Breast Cancer Mortality vs. Exercise and Breast Size in Runners and Walkers

Journal Article · Mon Dec 09 00:00:00 EST 2013 · PLoS ONE

DOI:https://doi.org/10.1371/journal.pone.0080616· OSTI ID:1627659

Williams, Paul T. ^[1]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Division; DOE/OSTI

Purpose: Identify predictors of breast cancer mortality in women who exercised below (,7.5 metabolic equivalent hours/ week, MET-hours/wk), at (7.5 to 12.5 MET-hours/wk), or above ($12.5 MET-hours/wk) recommended levels. Methods: Cox proportional hazard analyses of baseline pre-diagnosis MET-hours/wk vs. breast cancer mortality adjusted for follow-up age, race, baseline menopause, and estrogen and oral contraceptive use in 79,124 women (32,872 walkers, 46,252 runners) from the National Walkers’ and Runners’ Health Studies. Results: One-hundred eleven women (57 walkers, 54 runners) died from breast cancer during the 11-year follow-up. The decline in mortality in women who exercised $7.5 MET-hours/wk was not different for walking and running (P = 0.34), so running and walking energy expenditures were combined. The risk for breast cancer mortality was 41.5% lower for $7.5 vs. ,7.5 MET-hours/wk (HR: 0.585, 95%CI: 0.382 to 0.924, P = 0.02), which persisted when adjusted for BMI (HR: 0.584, 95%CI: 0.368 to 0.956, P = 0.03). Other than age and menopause, baseline bra cup size was the strongest predictor of breast cancer mortality, i.e., 57.9% risk increase per cup size when adjusted for MET-hours/wk and the other covariates (HR: 1.579, 95%CI: 1.268 to 1.966, P,0.0001), and 70.4% greater when further adjusted for BMI (HR: 1.704, 95%CI: 1.344 to 2.156, P = 1025 ). Breast cancer mortality was 4.0-fold greater (HR: 3.980, 95%CI: 1.894 to 9.412, P = 0.0001) for C-cup, and 4.7-fold greater (HR: 4.668, 95%CI: 1.963 to 11.980, P = 0.0004) for $D-cup vs. A-cup when adjusted for BMI and other covariates. Adjustment for cup size and BMI did not eliminate the association between breast cancer mortality and $7.5 MET-hour/wk walked or run (HR: 0.615, 95%CI: 0.389 to 1.004, P = 0.05). Conclusion: Breast cancer mortality decreased in association with both meeting the exercise recommendations and smaller breast volume.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
• Grant/Contract Number: AC03-76SF00098
• OSTI ID: 1627659
• Journal Information: PLoS ONE, Journal Name: PLoS ONE Journal Issue: 12 Vol. 8; ISSN 1932-6203
• Publisher: Public Library of Science
• Country of Publication: United States
• Language: English

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