Timing of exercise therapy when initiating adjuvant chemotherapy for breast cancer: a randomized trial

Aims The most appropriate timing of exercise therapy to improve cardiorespiratory fitness (CRF) among patients initiating chemotherapy is not known. The effects of exercise therapy administered during, following, or during and following chemotherapy were examined in patients with breast cancer. Methods and results Using a parallel-group randomized trial design, 158 inactive women with breast cancer initiating (neo)adjuvant chemotherapy were allocated to receive (1:1 ratio): usual care or one of three exercise regimens-concurrent (during chemotherapy only), sequential (after chemotherapy only), or concurrent and sequential (continuous) (n = 39/40 per group). Exercise consisted of treadmill walking three sessions/week, 20-50 min at 55%-100% of peak oxygen consumption (VO(2)peak) for approximate to 16 (concurrent, sequential) or approximate to 32 (continuous) consecutive weeks. VO(2)peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and approximate to 16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO(2)peak change between concurrent exercise and usual care during chemotherapy vs. VO(2)peak change between sequential exercise and usual care after chemotherapy [overall difference, -0.88 mL O-2 center dot kg(-1)center dot min(-1); 95% confidence interval (CI): -3.36, 1.59, P = 0.48]. In secondary analysis, continuous exercise, approximately equal to twice the length of the other regimens, was well-tolerated and the only strategy associated with significant improvements in VO(2)peak from baseline to post-intervention (1.74 mL O-2 center dot kg(-1)center dot min(-1), P < 0.001). Conclusion There was no statistical difference in CRF improvement between concurrent vs. sequential exercise therapy relative to usual care in women with primary breast cancer. The promising tolerability and CRF benefit of approximate to 32 weeks of continuous exercise therapy warrant further evaluation in larger trials.