Previous Anthracycline Treatment For Breast Cancer Impairs Exercise-induced Improvement In Cardiorespiratory Fitness

PURPOSE: To compare the effect of aerobic exercise on cardiorespiratory fitness (CRF) between long-term breast cancer survivors (BCSs) treated with anthracyclines, and healthy controls. METHODS: In this exercise intervention study, 70 survivors of breast cancer stage I-III, treated with anthracyclines (Epirubicin) between 2008-2012, and 69 age-matched cancer-naïve controls were included. Both groups underwent the same five-months exercise intervention, comprising thrice-weekly treadmill walking or running sessions, alternating between continuous, low-to-moderate intensity sessions and high-intensity interval sessions. CRF was measured as peak oxygen uptake (VO2peak) during a treadmill-based cardiopulmonary exercise test until exhaustion, pre and post intervention. Differences in mean changes between participants that completed both pre and post-intervention assessments in the two groups (BCSs n = 66, healthy controls n = 63) were compared with Analysis of Covariance (ANCOVA), adjusted for baseline values. RESULTS: The mean age of BCSs and healthy controls were 58.6 ± 6.0 and 57.8 ± 4.9 years, respectively, with comparable average BMI (kg/m2) of 26.7 ± 4.4 in BCSs and 28.1 ± 5.0 in healthy controls. Loss to follow-up were 5.7% in BCSs and 8.7% in healthy controls, while intervention adherence, evaluated per percentage attended sessions, was 78% and 80% for BCSs and healthy controls, respectively. The pre to post-intervention change in CRF was significantly different between the two groups (p < 0.005), where a 5.3% increase in VO2peak (mL·kg-1·min-1) was observed in BCSs, compared to a 10.7% increase in healthy controls (Table 1). Table 1. - Effect of exercise on cardiorespiratory fitness presented as mean ± SD Variable Baseline Training response X̄ Difference (P-value) BCSs Healthy controls BCSs Healthy controls VO2peak, L·min 2.06 ± 0.34 2.10 ± 0.34 0.10 ± 0.22 0.20 ± 0.18 -0.1 (0.002) VO2peak, mL·kg-1·min-1 27.9 ± 5.4 27.1 ± 5.4 1.47 ± 3.06 2.89 ± 2.50 -1.42 (0.005) VO2 at AT, L·min-1 1.71 ± 0.34 1.73 ± 0.36 0.01 ± 0.29 0.08 ± 0.22 -0.07 (0.030) CONCLUSION: Although aerobic exercise improves CRF in long-term BCSs treated with anthracyclines, the effect of exercise was impaired in BCSs compared to healthy individuals in this study. The study is funded by the Norwegian Cancer Society and Aktiv mot Kreft (Active Against Cancer