Exercise (physical activity) and breast cancer risk
This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.
Introduction: Women who get regular exercise (physical activity) have a lower risk of breast cancer than women who are inactive.
Overall, studies show regular exercise lowers breast cancer risk by 10-20 percent (see table below). This benefit is seen most clearly in postmenopausal women .
Learn more about exercise and breast cancer risk.
Learn about the strengths and weaknesses of different types of studies.
Read Komen’s perspective on physical activity and breast cancer risk.*
* Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.
Table notes: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
MET (metabolic equivalent) hours are often used as a measure of physical activity. One MET hour equals the energy used to sit quietly for one hour.
Different activities have different MET scores. Moderate activities, like mowing the lawn or slow dancing, range from 3-6 MET hours. Vigorous activities, like playing tennis or jogging, score higher than 6 MET hours. For example, walking is 3 MET hours and swimming is 7 MET hours.
Levels of Activity Compared
Relative Risk of Breast Cancer in Physically Active Women Compared to Inactive Women, RR (95% CI)
Before and after menopause combined
Prospective cohort studies
More than 42
NIH-AARP Diet and Health Study 
At least 4 hr/wk
Nurses’ Health Study 
27 or more
Cancer Prevention Study II-Nutrition Cohort 
More than 42 vs.
7 or more
French E3N cohort [5-6]
22-34 MET hr/wk recreational activity
34 or more MET hr/wk recreational activity
California Teachers Study 
5 or more hr/wk moderate physical activity
Women’s Health Initiative 
17 or more hr/wk
Iowa Women’s Health Study 
National Breast Cancer Screening Study-Canada 
At least 1 hr/day vigorous physical activity
Norwegian-Swedish Women’s Lifestyle and Health Cohort Study 
Breast Cancer Detection Demonstration Project Follow-up Study 
Netherlands Cohort Study 
More than 90 minutes/day of activity
U.S. Radiologic Technologies cohort 
At least 97
Walking/hiking at least 10 hr/wk
Nurses’ Health Study II [15-16]
27 or more
Pooled and meta-analyses
Nielson et al. 
Pizot et al. 
Kyu et al. 
Hardefeldt et al. 
World Cancer Research Fund International – Continuous Update Project 
Physical Activity Collaboration of the National Cancer Institute’s Cohort Consortium 
Matthews et al. 
1-7 MET hr/wk
8 to less than 15 MET hr/wk
15 to less than 30 MET hr/wk
30 or more MET hr/wk
Wu et al. 
10 MET hr/wk
African American Breast Cancer Epidemiology and Risk (AMBER) Consortium 
† Findings also showed a decreased risk of estrogen receptor-negative breast cancers among women with the highest levels of physical activity (more than 5 hours per week vs. inactive, RR was 0.53 (0.33-0.85)). There was no link between physical activity and risk of estrogen receptor-positive breast cancers.
‡ Findings for cohort studies only were similar. The relative risk for 13 cohort studies of premenopausal breast cancer risk was 0.83 (0.72-0.96). The relative risk for 26 cohort studies of postmenopausal breast cancer risk was 0.90 (0.85-0.95).
- Steindorf K, Ritte R, Eomois PP, et al. Physical activity and risk of breast cancer overall and by hormone receptor status: The European prospective investigation into cancer and nutrition. Int J Cancer. 132(7):1667-78, 2013.
- Cifu G, Arem H. Adherence to lifestyle-related cancer prevention guidelines and breast cancer incidence and mortality. Ann Epidemiol. 28(11):767-773, 2018.
- Eliassen AH, Hankinson SE, Rosner B, Holmes MD, Willett WC. Physical activity and risk of breast cancer among postmenopausal women. Arch Intern Med. 170(19):1758-64, 2010.
- Hildebrand JS, Gapstur SM, Campbell PT, Gaudet MM, Patel AV. Recreational physical activity and leisure-time sitting in relation to postmenopausal breast cancer risk. Cancer Epidemiol Biomarkers Prev. 22(10):1906-12, 2013.
- Tehard B, Friedenreich CM, Oppert JM, Clavel-Chapelon. Effect of physical activity on women at increased risk of breast cancer: results from the E3N cohort study. Cancer Epidemiol Biomarkers Prev. 15(1):57-64, 2006.
- Fournier A, Dos Santos G, Guillas G, et al. Recent recreational physical activity and breast cancer risk in postmenopausal women in the E3N cohort. Cancer Epidemiol Biomarkers Prev. 23(9):1893-902, 2014.
- Dallal CM, Sullivan-Halley J, Ross RK, et al. Long-term recreational physical activity and risk of invasive and in situ breast cancer: the California teachers study. Arch Intern Med. 167(4):408-15, 2007.
- Phipps AI, Chlebowski RT, Prentice R, et al. Body size, physical activity, and risk of triple-negative and estrogen receptor-positive breast cancer. Cancer Epidemiol Biomarkers Prev. 20(3):454-63, 2011.
- Bardia A, Hartmann LC, Vachon CM, et al. Recreational physical activity and risk of postmenopausal breast cancer based on hormone receptor status. Arch Intern Med. 166(22):2478-83, 2006
- Silvera SAN, Jain M, Howe GR, et al. Energy balance and breast cancer risk: a prospective cohort study. Breast Cancer Res Treat. 97(1):97-106, 2006.
- Margolis KL, Mucci L, Braaten T, et al. Physical activity in different periods of life and the risk of breast cancer: the Norwegian-Swedish Women’s Lifestyle and Health cohort study. Cancer Epidemiol Biomarkers Prev. 14(1):27-32, 2005.
- Leitzmann MF, Moore SC, Peters TM, et al. Prospective study of physical activity and risk of postmenopausal breast cancer. Breast Cancer Res. 10(5):R92, 2008.
- Dirx MJ, Voorrips LE, Goldbohm RA, et al. Baseline recreational physical activity, history of sports participation, and postmenopausal breast carcinoma risk in the Netherlands Cohort Study. Cancer. 92(6):1638-1649, 2001.
- Howard RA, Leitzmann MF, Linet MS, Freedman DM. Physical activity and breast cancer risk among pre- and postmenopausal women in the U.S. Radiologic Technologists cohort. Cancer Causes Control. 20(3):323-33, 2009.
- Colditz GA, Feskanich D, Chen WY, Hunter DJ, Willett WC. Physical activity and risk of breast cancer in premenopausal women. Br J Cancer. 89(5):847-51, 2003.
- Maruti SS, Willett WC, Feskanich D, Rosner B, Colditz GA. A prospective study of age-specific physical activity and premenopausal breast cancer. J Natl Cancer Inst. 100(10):728-37, 2008.
- Neilson HK, Farris MS, Stone CR, Vaska MM, Brenner DR, Friedenreich CM. Moderate-vigorous recreational physical activity and breast cancer risk, stratified by menopause status: a systematic review and meta-analysis. Menopause. 24(3):322-344, 2017.
- Pizot C, Boniol M, Mullie P, et al. Physical activity, hormone replacement therapy and breast cancer risk: A meta-analysis of prospective studies. Eur J Cancer. 52:138-54, 2016.
- Kyu HH, Bachman VF, Alexander LT, et al. Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013. BMJ. 354:i3857, 2016.
- Hardefeldt PJ, Penninkilampi R, Edirimanne S, Eslick GD. Physical activity and weight loss reduce the risk of breast cancer: a meta-analysis of 139 prospective and retrospective studies. Clin Breast Cancer. 18(4):e601-e612, 2018.
- Chan DSM, Abar L, Cariolou M, et al. World Cancer Research Fund International: Continuous Update Project-systematic literature review and meta-analysis of observational cohort studies on physical activity, sedentary behavior, adiposity, and weight change and breast cancer risk. Cancer Causes Control. 2019 Aug 30 [Epub ahead of print].
- Moore SC, Lee I-M, Weiderpass E, et al. Association of leisure-time physical activity with risk of 26 types of cancer in 1.44 million adults. JAMA Intern Med. 176(6):816-25, 2016.
- Matthews CE, Moore SC, Arem H, et al. Amount and intensity of leisure-time physical activity and lower cancer risk. J Clin Oncol. 2019 Dec 26 [Epub ahead of print].
- Wu Y, Zhang D, Kang S. Physical activity and risk of breast cancer: a meta-analysis of prospective studies. Breast Cancer Res Treat. 137(3):869-82, 2013.
- Gong Z, Hong CC, Bandera EV, et al. Vigorous physical activity and risk of breast cancer in the African American breast cancer epidemiology and risk consortium. Breast Cancer Res Treat. 159(2):347-56, 2016.