Long-term effects of exercise interventions on physical activity in breast cancer patients: a systematic review and meta-analysis of randomized controlled trials

BackgroundBenefits of exercise interventions for cancer patients are well established. This systematic review aimed to investigate the sustainability of exercise interventions with respect to physical activity behaviour of breast cancer patients in the longer term.MethodsThe databases Pubmed, Cochrane, Embase, and Web of Science were systematically searched for randomized controlled trials (RCTs) investigating aerobic exercise, resistance exercise, or combined exercise interventions in breast cancer patients and assessing physical activity at least 2 months after the intervention. Random-effect models were used to calculate standardized mean differences (SMD).ResultsA total of 27 RCTs with 4120 participants were included in the review, of which 11 RCTs with 1545 participants had appropriate data for the meta-analyses. Physical activity was mainly self-reported, and most exercise interventions were supervised. Exercise interventions tended to show a moderate significant effect up to 6 months for moderate to vigorous physical activity (SMD [95% CI] = 0.39 [0.07, 0.70]) and small, non-significant effects on total physical activity at 6 months (SMD [95% CI] = 0.14 [- 0.00, 0.28]) and up to 60 months after the intervention (SMD = 0.29 [-0.31, 0.90]). Differences between intervention characteristics, such as supervised versus unsupervised, were inconclusive due to the small number of RCTs.ConclusionsThe physical activity behaviour in breast cancer patients remained improved for several months beyond the end of exercise interventions, but effects were small to moderate and diminished over time. Future studies should clarify how to maintain a healthy level of physical activity after completion of an exercise intervention.