The effect of exercise training on endothelial function in postmenopausal women with breast cancer under aromatase inhibitor therapy

Background Breast cancer is the leading non-cardiovascular cause of death in women. In endocrine receptor positive women, aromatase inhibitors (AI) are the therapy of choice despite the fact that a decrease in systemic estrogen levels may result in endothelial dysfunction and eventually in cardiovascular disease. In this study, we assessed whether exercise training (ET), which has repeatedly shown to lead to an improvement of endothelial dysfunction, will also exert this effect in postmenopausal women with AI treated breast cancer. Methods Thirty two postmenopausal women with AI treated breast cancer were randomized to an intervention group (ET; 6 months, supervised training plus 6 months without intervention) or control group of usual care (UC; 12 months without intervention plus initial exercise counseling). Endothelial function was assessed via Reactive Hyperemia Index (RHI) measured non-invasively with the EndoPAT-System at baseline, 6 and 12 months. Results After 6 months of supervised ET, changes in maximal exercise capacity were significantly greater in ET than in UC ( increment W: 24.1 +/- 11.5 vs. 1.1 +/- 8.2 watts; p < 0.001). Even though 43.8% of all participants had endothelial dysfunction at baseline, there were no significant group differences in the changes of RHI between ET ( increment RHI: -0.1 +/- 1.04) and UC (0.02 +/- 0.75; p = 0.323) after 6 months. Conclusion Even though ET led to significantly greater improvement in exercise capacity in postmenopausal women with AI treated breast cancer than exercise counseling only, it did not exert any measurable effects on endothelial dysfunction.