1 Role of Physical Activity In Breast Cancer

Abstract : Breast cancer is the most common cancer among women. The number of breast cancer survivors has increased due to screening and improved treatment methods, which makes it important to increase knowledge on their health and well-being. Physical activity has been reported to improve quality of life, decrease fatigue and reduce all-cause and breast cancer-specific mortality in breast cancer survivors. In physically active subjects, the risk reduction averaged 25–30%. Breast cancer is one of the most commonly diagnosed types of cancer in women. Its pathogenesis involves genetic, hormonal, and environmental factors6. A large body of evidence indicates that physical activity has positive effects on every aspect of breast cancer evolution, including prevention, medical treatment, and aftercare clinical settings. Thus, different types of exercise can influence the prevention and progression of the disease through several common mechanisms, such as reduction of insulin resistance and improvement of immunity and cardiovascular function. Furthermore, acute and chronic symptoms of breast cancer, such as cachexia, muscle mass loss, fatigue, cardiotoxicity, weight gain, hormone alterations, bone loss, and psychological adverse effects, may all be favorably influenced by regular exercise.7 The potential role of exercise in reducing the intensity of the adverse effects that result from breast cancer and anticancer treatment is also discussed1. According to published data, 30–60 min of exercise per day at a moderate intensity is regarded as the optimal duration. Furthermore, physical activity plays an important role in the therapy of breast cancer, not only after finishing but already during treatment. The beneficial effects of physical activity may manifest themselves in circulating levels of insulin, insulin-growth factors (IGFs) I and II and their binding proteins (IGFBPs), or inflammatory biomarkers. The aim of this report was to review available randomized controlled trials (RCTs) on the effects of physical activity on biomarkers in breast cancer survivors. Five RCTs reported statistically significant effects of physical activity on insulin, IGF-I, IGF-II and IGFBP-3 in breast cancer survivors, but the results were not consistent. None of four RCTs found any evidence for a role of investigated interleukins. One trial reported some evidence that exercise may decrease C-reactive protein levels. In conclusion, available RCTs have produced some evidence that physical activity may result in beneficial changes in levels of insulin, IGFs, IGFBPs, and inflammatory biomarkers in breast cancer survivors. However, further larger RCTs on physical activity and biomarkers in breast cancer survivors are warranted.

Keyword : Physical activity, Intervention, Breast cancer survivors, Insulin, Insulin-growth factors, Inflammation