The Impact of Exercise Training on Breast Cancer

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.

Keywords: Breast cancer; N-methyl-N-nitrosourea; physical training.

Figure 1. Immunohistochemical expression of Ki-67 proliferation antigen. Magnification ×200.

Figure 2. The expression of Ki-67 antigen in low- (LIT), moderate-(MIT), and high-intensity training (HIT) and untrained (SC) studygroups. The secondary prevention model (A), the comparison betweenthe secondary and primary prevention models (B) and the primary prevention model (C) (subject of our previous study; 4).