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

PURPOSE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.

IMPLICATIONS FOR CANCER SURVIVORS: 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.