Effect of Six Months of Aerobic Exercise on Plasma Interleukin-6 and Tumor Necrosis Factor-Alpha as Breast Cancer Risk Factors in Postmenopausal Women: A Randomized Controlled Trial

Increased physical activity is associated with a reduction in the risk of breast cancer; however, the exact mechanism of the reduction is not yet completely known. This study aimed to investigate the effect of six months of aerobic exercise on the plasma interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α) levels as breast cancer risk factors in postmenopausal women. This study was a randomized controlled trial. We randomly assigned 41 postmenopausal, sedentary women aged 50 to 74 to either an exercise or a control group. The intervention involved facility-based aerobic exercise (three days/week, at 70 - 80% of the maximum heart rate, for six months). Twenty-seven women completed the study. The plasma IL-6 level decreased by 21.3% in the exercisers and by 6.9% in the controls, and the intervention effect was significant (P = 0.001). The plasma TNF-α level decreased by 17.1% and 10.8% in the exercisers and controls, respectively, although the effect of exercise was not statistically significant (P = 0.28). Overall, long-term aerobic exercise may result in a decreased IL-6 concentration. We suggest that regular aerobic exercise can favorably alter the inflammatory profile, which is a known risk factor in breast cancer development, in postmenopausal women.