Regular, Moderate Physical Activity Decreases Breast Cancer Risk in Postmenopausal Women
Postmenopausal women who in the previous 4 years had undertaken the equivalent of at least 4 hours of walking per week had a 10% decreased risk of invasive breast cancer compared with women who were less active, according to a new study. The findings suggest that regular physical activity, even of modest intensity, has an impact on a woman’s breast cancer risk after menopause. The study by Fournier et al is published in Cancer Epidemiology, Biomarkers & Prevention.
Study Methodology
The researchers analyzed data obtained from biennial questionnaires completed by 59,308 postmenopausal women enrolled in E3N, the French component of the European Prospective Investigation into Cancer and Nutrition (EPIC) study, between 1993 and 2005 (8.5 years postmenopause on average). During that time, 2,155 of the women were diagnosed with a first primary invasive breast cancer.
The total amount of self-reported recreational physical activity was calculated in metabolic equivalent task-hours (MET-h) per week and included duration that participants spent walking, cycling, and engaging in sports during 2 typical weeks over the past year, one in summer and one in winter.
Results
The women who in the previous 4 years had undertaken 12 or more MET-h of physical activity each week had a 10% decreased risk of invasive breast cancer compared with women who were less active. Women who undertook this level of physical activity between 5 and 9 years earlier, but were less active in the 4 years prior to the final data collection did not have a decreased risk for invasive breast cancer.
The breast cancer risk–reducing effects of 12 or more MET-h per week of recreational physical activity were independent of body mass index, weight gain, waist circumference, and the level of activity from 5 to 9 years earlier.
“Twelve MET-h per week corresponds to walking 4 hours per week or cycling or engaging in other sports 2 hours per week and it is consistent with the World Cancer Research Fund recommendations of walking at least 30 minutes daily,” said Agnés Fournier, PhD, a researcher in the Centre for Research in Epidemiology and Population Health at the Institut Gustave Roussy in Villejuif, France, and lead author the study, in a statement. “So, our study shows that it is not necessary to engage in vigorous or very frequent activities. Even walking 30 minutes per day is beneficial.”
The American Cancer Society (ACS) recommends that adults engage in at least moderate activity for 30 minutes or more on 5 or more days per week, to reduce the risk of several types of cancer, including breast and colon. According to ACS, 45 minutes or more of moderate to vigorous activity on 5 or more days per week may further enhance reductions in the risk of breast and colon cancer.
Françoise Clavel-Chapelon, PhD, of Institut Gustave Roussy, is the corresponding author for the Cancer Epidemiology, Biomarkers & Prevention article.
The study was funded by the Institut National du Cancer, the Fondation de France, and the Institut de Recherche en Santé Publique. The E3N cohort is financially supported by the Institut National du Cancer, the Mutuelle Générale de l’Education Nationale, the Institut de Cancérologie Gustave Roussy, and the Institut National de la Santé et de la Recherche Médicale.
The researchers reported no conflicts of interest.
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