Cancer patients with high muscle strength and cardiorespiratory fitness (CRF) had a significantly lower risk of death from any cause, including those with advanced cancers, a large retrospective review showed.

All-cause mortality risk declined by as much as 46% among patients with high muscle strength and CRF as compared with those who had low muscle strength and CRF. When assessed by incremental changes in unit of measure, muscle strength had a statistically significant association with all-cause mortality and CRF with cancer-specific mortality.

Patients with advanced cancers benefited as much as those with earlier-stage disease, reported Robert Newton, ScD, PhD, of Edith Cowan University in Joondalup, Australia, and co-authors in the British Journal of Sports Medicine.

“Assessing physical fitness, particularly muscle strength and CRF, is crucial for predicting mortality in cancer patients,” the authors stated. “Implementing tailored exercise prescriptions to enhance these physical fitness components throughout the cancer continuum may contribute to reducing cancer-related mortality.”

“Given these findings, tailored exercise prescriptions to improve muscle strength and CRF in patients with cancer may contribute to reducing cancer-related mortality,” they added.

Based on data from published studies involving almost 47,000 adults, the findings add to an extensive volume of evidence supporting a favorable effect of muscle strength and fitness on cancer outcomes.

For example, a recent analysis of studies involving 1.3 million people of all ages identified significant associations between “muscle-strengthening activities” and total cancer mortality. Combined muscle-strengthening and aerobic activities also were associated with a larger reduction in the risk of cancer death. Conversely, lower levels of muscle mass and strength have a significant inverse association with all-cause mortality in healthy adults.

Both the American Society of Clinical Oncology and the American Cancer Society have clinical guidelines that address behavioral/lifestyle factors, including physical activity, that can influence cancer outcomes

Newton and colleagues sought to address a limitation of many prior studies: a focus on healthy individuals and subsequent cancer diagnoses.

“To date, there is no available research investigating whether these physical fitness components are associated with a lower risk of mortality in individuals who have been diagnosed with cancer,” they noted. “Additionally, the associations between these components and cancer-specific mortality remain to be determined.”

The investigators performed a systematic review of medical literature published up to August 2023. They limited the search to prospective observational cohort studies that assessed the association between muscle strength, CRF, or both, and mortality in adult patients with cancer. The primary outcomes were all-cause and cancer-specific mortality.

The search identified 42 studies that involved a combined total of 46,694 patients, who had a median age of 64 and median body mass index of 24.8. The studies included 26 with multiple types of cancer, nine limited to patients with lung cancer, two limited to gastric cancer, and one each limited to pancreatic, breast, glioma, colon, and bladder cancer.

In 35 studies, cut-off values were established to compare high versus low muscle strength and/or CRF, and 12 studies examined changes as per unit increment.

All of the studies used a hand grip test to define muscle strength. Of the studies that examined CRF, 14 used the cardiopulmonary exercise test and four used the 6-minute walk test. Studies included in the analyses defined high versus low muscle strength and CFS by means of pre-specified cutoff values and by per-unit incremental change in the values (such as a 1-MET incremental change in physical activity).

Overall, patients with high muscle strength had a 31% reduction in all-cause mortality risk (95% CI 0.61-0.78, PP=0.005). All-cause mortality risk declined by 8-46% in patients with advanced cancers and by 19-41% in patients with lung or digestive cancer.

Seven trials evaluated the association between muscle strength and all-cause mortality by per-unit incremental change in values. The analysis showed an 11% reduction in all-cause mortality risk with each unit increase in muscle strength (95% CI 0.82-0.97, P=0.005).

Six studies that examined incremental changes in CRF showed no significant association with all-cause mortality (HR 0.89, 95% CI 0.76-1.04) or cancer-specific mortality (HR 0.34, 95% CI 0.08-1.38). However, a multivariable analytic model based on two studies showed an 18% decrease in cancer-specific mortality with each unit increase in CRF (95% CI 0.69-0.98, P=0.03).

“Collectively, [these] findings emphasize the importance of examining muscle strength and CRF in clinical practice to determine the mortality risk in patients with cancer, especially those with advanced cancer,” the authors concluded.