The effect of physical activity on sex hormone levels in women. Implications for breast cancer risk

Breast cancer is the most commonly diagnosed neoplastic disease in women, which leads to a significant deterioration in the quality of life and a reduction in the ability of women to function normally in everyday life. The main risk factor for breast cancer in both premenopausal and postmenopausal women is exposure to high levels of endogenous estrogen. It takes many years for neoplasia to develop, but lowering estrogen levels has been observed to reduce the risk of both a new diagnosis and recurrence of breast cancer. Observational studies have found that exercise reduces the level of bioavailable sex hormones, and thus may reduce the risk of developing breast cancer. Currently available evidence clearly shows that adequate levels of physical activity are associated with a 25–30% reduction in the average risk of breast cancer in women and play a role in its treatment. This review summarizes the data available in the literature on the effect of physical activity on the level of sex hormones in women, while presenting the biological mechanisms underlying the relationship between physical activity and the development of breast cancer. This issue requires further research, but already now, extensive educational campaigns are needed which can be aimed at young women to inform them on the possibility of significantly reducing their risk of breast cancer by introducing physical activity into their everyday lives.