Abstract A80: Physical activity reduces breast cancer risk in African American women

Abstract

Abstract Background: The reported inverse relationship between physical activity and breast cancer risk is under constant scrutiny, and the evidence is inconsistent. Furthermore, few studies have been conducted with African Americans. Methods: A population-based case-control study identified 97 cases and 102 controls from the Washington, DC, area. A self-report physical activity questionnaire elicited responses on walking for exercise and vigorous physical activity (e.g., running, aerobics, etc.) in the past year. Responses were used to calculate a metabolic equivalent (MET) score [MET-hours/week= hours/week vigorous activityx7+ hours/week walking x3]. The MET score was categorized into low, medium and high tertiles. Multivariate logistic regression examined the association between physical activity and breast cancer. Results: African American women who engaged in vigorous physical activity (> 2 hours/week in the past year) had a 64% reduced risk of breast cancer compared to those who did not participate in any vigorous activity (odds ratio, OR = 0.36; 95% confidence interval, CI = 0.17-0.75). We also found a 64% reduced breast cancer risk in women with a high versus low tertile of total activity (OR = 0.36; 95% CI = 0.16-0.79). For postmenopausal women, vigorous physical activity and total activity (high versus low tertile) also had an inverse relationship with breast cancer (p<.05). Conclusion: Modest levels of physical activity can reduce breast cancer risk in African American women. Impact: Targeted efforts to encourage more African American women to engage in modest levels of physical activity may positively impact disparate breast outcomes in this group. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A80.