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Background: Whether structured exercise therapy improves chemotherapy delivery, tolerability, and tumor response is unclear. Methods: This was a secondary analysis of a phase 2 trial investigating exercise therapy (n = 72) versus usual care (n = 72) in patients with primary breast cancer. Exercise therapy comprised individualized treadmill walking three times weekly for 20–50 minutes per session at 55%–100% of pretreatment exercise capacity. Chemotherapy delivery was assessed according to the relative dose intensity (RDI), tolerability was assessed according to patient‐reported outcomes and blood laboratory values, and response was assessed based on the pathologic complete response rate in patients who received neoadjuvant chemotherapy. Results: In the exercise therapy group, 51 patients (71%) reached 100% RDI (median, 100%; interquartile range, 100%–100%) compared with 41 patients (57%) in the usual care group (median, 100%; interquartile range, 95%–100%; p =.08). Tolerability was similar in both groups; the rates of grade 3 or higher neutropenia and anemia were 22% versus 39% and 7% versus 10% in the exercise and usual care groups, respectively. In patients who received anthracyclines (n = 104), 41 (77%) had 100% chemotherapy RDI in the exercise therapy group versus 29 (57%) in the usual care group (p =.026). In the neoadjuvant chemotherapy subgroup (n = 51 tumors), the postneoadjuvant therapy (yp) pathologic complete response (ypT0ypN0) rate was 27% (95% confidence interval, 12%–50%) in the exercise therapy group compared with 28% (95% confidence interval, 13%–47%) in the usual care group (p >.9). Conclusions: In patients with primary breast cancer, exercise therapy was associated with improved delivery of anthracycline‐based chemotherapy. Although exercise therapy was not significantly associated with tumor response, effects varied by tumor subtype (trial registration: Clinicaltrials.gov identifier NCT01943695). This was a preplanned, secondary analysis of a phase 2 trial investigating exercise therapy versus usual care during (neo)adjuvant chemotherapy for primary breast cancer. Exercise therapy was associated with improved delivery of anthracycline‐based chemotherapy, although tumor response varied by subtype. [ABSTRACT FROM AUTHOR]

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 (VO2peak) for ≈16 (concurrent, sequential) or ≈32 (continuous) consecutive weeks. VO2peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and ≈16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO2peak change between concurrent exercise and usual care during chemotherapy vs. VO2peak change between sequential exercise and usual care after chemotherapy [overall difference, −0.88 mL O2·kg−1·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 VO2peak from baseline to post-intervention (1.74 mL O2·kg−1·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 ≈32 weeks of continuous exercise therapy warrant further evaluation in larger trials. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate the prevalence of abnormal cardiopulmonary responses to exercise and pathophysiological mechanism(s) underpinning exercise intolerance across the continuum of breast cancer (BC) care from diagnosis to metastatic disease., Methods: Individual participant data from four randomized trials spanning the BC continuum ([1] prechemotherapy [n = 146], [2] immediately postchemotherapy [n = 48], [3] survivorship [n = 138], and [4] metastatic [n = 47]) were pooled and compared with women at high-risk of BC (BC risk; n = 64). Identical treadmill-based peak cardiopulmonary exercise testing protocols evaluated exercise intolerance (peak oxygen consumption; V̇O2peak) and other resting, submaximal, and peak cardiopulmonary responses. The prevalence of 12 abnormal exercise responses was evaluated. Graphical plots of exercise responses were used to identify oxygen delivery and/or uptake mechanisms contributing to exercise intolerance. Unsupervised, hierarchical cluster analysis was conducted to explore exercise response phenogroups., Results: Mean V̇O2peak was 2.78 ml O2.kg-1·min-1 (95% confidence interval [CI], -3.94, -1.62 mL O2.kg-1·min-1; P < 0.001) lower in the pooled BC cohort (52 ± 11 yr) than BC risk (55 ± 10 yr). Compared with BC risk, the pooled BC cohort had a 2.5-fold increased risk of any abnormal cardiopulmonary response (odds ratio, 2.5; 95% confidence interval, 1.2, 5.3; P = 0.014). Distinct exercise responses in BC reflected impaired oxygen delivery and uptake relative to control, although considerable inter-individual heterogeneity within cohorts was observed. In unsupervised, hierarchical cluster analysis, six phenogroups were identified with marked differences in cardiopulmonary response patterns and unique clinical characteristics., Conclusions: Abnormal cardiopulmonary response to exercise is common in BC and is related to impairments in oxygen delivery and uptake. The identification of exercise response phenogroups could help improve cardiovascular risk stratification and guide investigation of targeted exercise interventions., (Copyright © 2023 by the American College of Sports Medicine.)