Association of muscle strength and cardiorespiratory fitness with all-cause and cancer-specific mortality in patients diagnosed with cancer: a systematic review with meta-analysis

OBJECTIVES: To examine the association between muscle strength and cardiorespiratory fitness (CRF) with all-cause and cancer-specific mortality in patients diagnosed with cancer, and whether these associations are affected by type and/or stage of cancer. METHOD: A systematic review with meta-analysis was carried out. Five bibliographic databases were searched to August 2023. RESULTS: Forty-two studies were included (n=46 694). Overall, cancer patients with high muscle strength or CRF levels (when dichotomised as high vs low) had a significant reduction in risk of all-cause mortality by 31-46% compared with those with low physical fitness levels. Similarly, a significant 11% reduction was found for change per unit increments in muscle strength. In addition, muscle strength and CRF were associated with an 8-46% reduced risk of all-cause mortality in patients with advanced cancer stages, and a 19-41% reduced risk of all-cause mortality was observed in lung and digestive cancers. Lastly, unit increments in CRF were associated with a significant 18% reduced risk of cancer-specific mortality. CONCLUSION: High muscle strength and CRF were significantly associated with a lower risk of all-cause mortality. In addition, increases in CRF were associated with a reduced risk of cancer-specific mortality. These fitness components were especially predictive in patients with advanced cancer stages as well as in lung and digestive cancers. This highlights the importance of assessing fitness measures for predicting mortality in cancer patients. Given these findings, tailored exercise prescriptions to improve muscle strength and CRF in patients with cancer may contribute to reducing cancer-related mortality.