Effectiveness of exercise modalities on breast cancer patient outcomes: a systematic review and meta-analysis

The effects of exercise in patients with breast cancer (BC), has shown some profit, but consistency and magnitude of benefit remains unclear. We aimed to conduct a meta-analysis to assess the benefits of varying types of exercises in patients with BC.

Literature search was conducted across five electronic databases (MEDLINE, Web of Science, Scopus, Google Scholar and Cochrane) from 1st January 2000 through 19th January 2024. Randomized controlled trials (RCTs) assessing the impact of different types of exercise on outcomes related to fitness and quality of life (QOL) in patients with BC were considered for inclusion. Outcomes of interest included cardiorespiratory fitness (CRF), health-related quality of life (HRQOL), muscle strength, fatigue and physical function. Evaluations were reported as mean differences (MDs) with 95% confidence intervals (CIs) and pooled using random effects model. A p value < 0.05 was considered significant.

Thirty-one relevant articles were included in the final analysis. Exercise intervention did not significantly improved the CRF in patients with BC when compared with control according to treadmill ergometer scale (MD: 4.96; 95%Cl [-2.79, 12.70]; P = 0.21), however exercise significantly improved CRF according to cycle ergometer scales (MD 2.07; 95% Cl [1.03, 3.11]; P = 0.0001). Physical function was significantly improved as well in exercise group reported by 6-MWT scale (MD 80.72; 95% Cl [55.67, 105.77]; P < 0.00001). However, exercise did not significantly improve muscle strength assessed using the hand grip dynamometer (MD 0.55; 95% CI [-1.61, 2.71]; P = 0.62), and fatigue assessed using the MFI-20 (MD -0.09; 95% CI [-5.92, 5.74]; P = 0.98) and Revised Piper scales (MD -0.26; 95% CI [-1.06, 0.55] P = 0.53). Interestingly, exercise was found to improve HRQOL when assessed using the FACT-B scale (MD 8.57; 95% CI [4.53, 12.61]; P < 0.0001) but no significant improvements were noted with the EORTIC QLQ-C30 scale (MD 1.98; 95% CI [-1.43, 5.40]; P = 0.25).

Overall exercise significantly improves the HRQOL, CRF and physical function in patients with BC. HRQOL was improved with all exercise types but the effects on CRF vary with cycle versus treadmill ergometer. Exercise failed to improve fatigue-related symptoms and muscle strength. Large RCTs are required to evaluate the effects of exercise in patients with BC in more detail.