Breast cancer risk reduced by daily exercise

Lauren McCullough, MSPH, of the University of North Carolina at Chapel Hill conducted a population-based study in pre- and post-menopausal women, investigating the impact of exercise on incidence of breast cancer. The study involved 1504 women with cancer and 1555 women without cancer.

Women who engaged in physical exercise 10 to 19 hours per week during their reproductive years showed a 1/3 reduction in breast cancer compared with women who got minimal exercise. Similarly, women after menopause who exercised 9 to 17 hours per week showed a 30% reduction in breast cancer.

Interestingly, exercising more than 19 or 17 hours in pre- and post-menopausal women, respectively, did not produce better results in reducing the incidence of breast cancer. The results were actually worse. In addition, significant weight gain seems to reduce the benefits of exercise in preventing cancer.

There is no consensus as to why exercise is beneficial in reducing cancer rates.  However, the research group noted a number of possible explanations: it may reduce the level of insulin resistance which has been associated with cancer, or inflammation which is also related to cancer incidence.  Alternatively, exercise may simply reduce the tendency toward obesity that is strongly associated with raised cancer rates.

Source: MedPage Today