Exercise may cut breast cancer risk in African Americans

According to a new study in Cancer Epidemiology Biomarkers & Prevention, brisk walking or vigorous exercise may help reduce risk of breast cancer in African-American women.

Researchers from Boston University’s Slone Epidemiology Center used prospective data from the Black Women’s Health Study on 44,708 African-American women aged 30 years or older at the time of enrollment to assess vigorous exercise in relation to the overall incidence of invasive breast cancer (n = 1364), estrogen receptor-positive cancer (n = 688), and estrogen receptor(ER)-negative cancer (n =405). More than 307,672 person years of follow-up were studied and Cox proportional hazards models were used to estimated incidence rate ratios (IRR) and 95% confidence intervals (CI).

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Vigorous exercise at baseline and brisk walking for at least 7 hours per week were inversely associated with overall breast cancer incidence (P trend = 0.05):the IRR for ≥7 hour/week relative to <1 hour/week was 0.74 (95% CI 0.57-0.96). ER status had no impact on the association. Breast cancer incidence was not associated with vigorous exercise in high school or at ages 21 or 30. Interestingly, significant periods of inactivity, such as watching television or sitting for long periods while at work, were not significantly associated with breast cancer incidence.

Investigators concluded that a high level of vigorous exercise could be associated with a reduced incidence of breast cancer in African-American women. They believe that the findings could provide information on a potentially modifiable risk factor.

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