Abstract 142: Physical activity prior to diagnosis and risk of fatal breast cancer.
Authors: Fortner Renée T. , Tworoger Shelley S. , Tamimi Rulla M. , Rosner Bernard , Willet Walter C. , Hankinson Susan E. , Eliassen A. Heather 
Published: August 2014

Data suggest an inverse association between physical activity and risk of breast cancer, as well as lower risk of death among breast cancer survivors with higher levels of physical activity. Breast cancer survival rates are relatively high. However, lifestyle factors prior to diagnosis may be related to whether subsequent breast cancer is aggressive, and ultimately fatal. We examined this association in the Nurses’ Health Study (NHS), among 105,387 women with 18 years of follow-up (1986-2010). Physical activity was assessed every 2-4 years on the NHS biennial questionnaire; new cases of breast cancer were reported on the biennial questionnaire and followed-up via medical record review. Cause of death was determined through review of medical records and death certificates. Overall, 762 fatal cases were identified during follow-up among 8356 total cases of breast cancer. We used Cox proportional hazards models to estimate the association between the cumulative average of physical activity over follow-up and fatal breast cancer. In multivariable models, higher physical activity was significantly inversely associated with fatal breast cancer risk. Relative to &lt;3 MET-hrs of activity per week, participation in activities totaling 3 to &lt; 9, 9 to &lt; 18, 18 to &lt;27, and ≥27 MET-hrs/week were associated with reductions in risk of 21% (95% CI: 0.63-1.00), 35% (95% CI: 0.51-0.82), 41% (95% CI: 0.45-0.78), and 43% (95% CI: 0.43-0.74), respectively (ptrend&lt;0.001). Results were virtually unchanged after additionally adjusting for BMI (e.g. ≥27 vs. &lt;3 MET-hrs/week total activity RR=0.56 (95% CI: 0.43-0.73, ptrend&lt;0.001)). Results for fatal breast cancer were stronger than those for overall breast cancer. Our findings suggest higher physical activity before breast cancer diagnosis is associated with reduced risk of fatal breast cancer. Our results extend existing evidence supporting an inverse association between physical activity and breast cancer risk to the outcome of fatal breast cancer.

Physical Activity and risk of overall and fatal breast cancer: Nurses’ Health Study, 1986–2010 Fatal Breast Cancer* All Breast Cancer* MET-hrs/week HR 95% CI HR 95% CI &lt;3 1.00 ref 1.00 ref 3 - &lt;9 0.79 0.63 - 1.00 0.94 0.86 - 1.02 9 - &lt;18 0.65 0.51 - 0.82 0.86 0.79 - 0.93 18 - &lt;27 0.59 0.45 - 0.78 0.83 0.75 - 0.91 27+ 0.57 0.43 - 0.74 0.78 0.71 - 0.86 ptrend &lt;0.001 &lt;0.001 *Adjusted for age, age at first birth/parity, age at menarche, menopausal status, past oral contraceptive use, smoking, alcohol use, family history of breast cancer, history of benign breast disease

Citation Format: Renée T. Fortner, Shelley S. Tworoger, Rulla M. Tamimi, Bernard Rosner, Walter C. Willet, Susan E. Hankinson, A. Heather Eliassen. Physical activity prior to diagnosis and risk of fatal breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 142. doi:10.1158/1538-7445.AM2013-142