Exercise interventions for people undergoing multimodal cancer treatment that includes surgery

People undergoing multimodal cancer treatment are at an increased risk of adverse events. Physical fitness significantly reduces following cancer treatment, which is related to poor postoperative outcome. Exercise training can stimulate skeletal muscle adaptations, such as increased mitochondrial content and improved oxygen uptake capacity may contribute to improved physical fitness.

To determine the effects of exercise interventions for people undergoing multimodal treatment for cancer, including surgery, on physical fitness, safety, health-related quality of life (HRQoL), fatigue, and postoperative outcomes.

We searched electronic databases of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, SPORTDiscus, and trial registries up to October 2018.

We included randomised controlled trials (RCTs) that compared the effects of exercise training with usual care, on physical fitness, safety, HRQoL, fatigue, and postoperative outcomes in people undergoing multimodal cancer treatment, including surgery.

Two review authors independently selected studies, performed the data extraction, assessed the risk of bias, and rated the quality of the studies using Grading of Recommendation Assessment, Development, and Evaluation (GRADE) criteria. We pooled data for meta-analyses, where possible, and reported these as mean differences using the random-effects model.

Eleven RCTs were identified involving 1067 participants; 568 were randomly allocated to an exercise intervention and 499 to a usual care control group. The majority of participants received treatment for breast cancer (73%). Due to the nature of the intervention, it was not possible to blind the participants or personnel delivering the intervention. The risk of detection bias was either high or unclear in some cases, whilst most other domains were rated as low risk. The included studies were of moderate to very low-certainty evidence. Pooled data demonstrated that exercise training may have little or no difference on physical fitness (VO₂ max) compared to usual care (mean difference (MD) 0.05 L/min^-1, 95% confidence interval (CI) -0.03 to 0.13; I² = 0%; 2 studies, 381 participants; low-certainty evidence). Included studies also showed in terms of adverse effects (safety), that it may be of benefit to exercise (8 studies, 507 participants; low-certainty evidence). Furthermore, exercise training probably made little or no difference on HRQoL (EORTC global health status subscale) compared to usual care (MD 2.29, 95% CI -1.06 to 5.65; I² = 0%; 3 studies, 472 participants; moderate-certainty evidence). However, exercise training probably reduces fatigue (multidimensional fatigue inventory) compared to usual care (MD -1.05, 95% CI -1.83 to -0.28; I² = 0%; 3 studies, 449 participants moderate-certainty evidence). No studies reported postoperative outcomes.

The findings should be interpreted with caution in view of the low number of studies, the overall low-certainty of the combined evidence, and the variation in included cancer types (mainly people with breast cancer), treatments, exercise interventions, and outcomes. Exercise training may, or may not, confer modest benefit on physical fitness and HRQoL. Limited evidence suggests that exercise training is probably not harmful and probably reduces fatigue. These findings highlight the need for more RCTs, particularly in the neoadjuvant setting.