The role of physical exercise in the development of breast cancer
AbstractBreast cancer is one of the most common types of cancer among women worldwide. Epidemiological and experimental studies confirm the beneficial effects of physical exercise both in patients who have suffered a relapse and in those who are in the course of a treatment. Researchers suggest that regular physical effort performed 3-5 times a week at 20-40 MET reduces the risk of development of breast cancer. Scientific evidence suggests that aerobic training can be safe and effective even during the oncological treatment, which, depending on the stage of the disease, may consist of surgical treatment combined with chemotherapy, radiotherapy or hormone therapy. In addition, it significantly improves the function of the circulatory and respiratory systems, reduces fatigue and improves the quality of life of patients struggling with the disease. There are many theories on the mechanisms that are triggered by aerobic workout. Despite the numerous studies on this subject, which have been conducted over the years, we still cannot say how physical activity reduces the risk of development of breast cancer. The most frequently mentioned biological mechanisms include the influence of oestrogen, metabolic hormones, growth factor, inflammatory markers, response from the immune system, insulin resistance and oxidative stress. Many studies into the process of carcinogenesis are carried out in laboratory conditions on animals. Due to application of different experimental models, the results of such studies are often ambiguous. Nevertheless, scientists see a huge potential in this kind of experiments, because some of them have already attested to the protective effects of physical exercise against the appearance of breast cancer, but also they have increased our understanding of the processes through which this risk is reduced. Perhaps, in the future physical activity will become a part of a cancer treatment thanks to the results of such studies.