Abstract
BACKGROUND/AIM: Physical exercise is increasingly considered by many authors to be a factor reducing the risk of cancer development and premature cancer-related death. Data indicate higher cure rates and longer times of survival in cancer patients who regularly exercise. MATERIALS AND METHODS: A total of 50 female Sprague-Dawley rats were used in the experiment. Animals at 1 month of age were intraperitoneally injected with N-methyl-N-nitrosourea. Three months following drug administration, rats underwent supervised physical training. The animals were divided into four groups: control untrained group and 3 groups trained with different intensities - i.e. low, moderate and high. Routine histopathological examination of tumors was performed and mitotic activity was assessed by immunohistochemical expression of the Ki-67 antigen. RESULTS: Ki-67 antigen expression was observed in all analyzed tumors. The increase in Ki-67 antigen expression correlated positively with the increase in training intensity. CONCLUSION: It can be assumed that low-intensity physical training is safe for patients with breast cancer. However, moderate- and high-intensity training may induce tumor cell proliferation worsening patients' prognosis.