Eight-year follow-up of patient-reported outcomes in patients with breast cancer participating in exercise studies during chemotherapy

Numerous randomized controlled trials (RCTs) have shown beneficial exercise effects on fatigue, anxiety and depression and health-related quality of life (HRQoL) in breast cancer (BC) patients during and shortly after treatment. Here, we investigated the long-term effects of exercise during chemotherapy for BC on these outcomes. We invited participants of two highly comparable RCTs that investigated the effects of exercise (EX) (versus usual care (UC)) during chemotherapy in patients with non-metastatic BC (N = 357) to participate in an 8-year follow-up. In both trials, fatigue, anxiety and depression and HRQoL were assessed using the same questionnaires, at multiple timepoints. Linear mixed-effect models were used to compare study arms over time. In total, 156 participants (EX = 82; UC = 74) completed the follow-up questionnaires. EX reported comparable general (between-group difference 0.73, 95% confidence interval (- 0.35; 1.80), ES = 0.18) and physical fatigue (0.55 (- 0.55; 1.65), ES = 0.13), small but statistically significantly higher levels of anxiety (1.24 (0.47 to 2.00), ES = 0.39) and depression (1.10 (0.34; 1.85), ES = 0.38), significantly lower global HRQoL (- 5.99 (- 10.65; - 1.32), ES = 0.34) and comparable summary HRQoL (- 1.90 (- 4.70; 0.89), ES = 0.16) compared to UC. No long-term beneficial effects of exercise during chemotherapy on BC patients' fatigue, anxiety, depression or HRQoL were observed. The less favourable outcomes for mood and HRQoL that were observed 8 years after participation in an exercise intervention may be explained by selective loss-to-follow-up. The results highlight the need to incorporate strategies that promote physical activity maintenance after participation in an exercise programme to also counteract long-term detrimental side effects of cancer treatment.