Authors: Francesco Bettariga, Robert Newton 

Exercise Medicine Research Institute, Edith Cowan University, Joondalup, Australia 

School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia

Why is this study important?

Every year, there are around 20 million new cancer cases and 10 million cancer-related deaths worldwide, making cancer one of the leading causes of death and illness. Although treatments to fight cancer have dramatically improved in the last decades, and they have contributed to reducing mortality and morbidity, physical activity remains underutilized and is still not considered an essential component of cancer care. This is despite growing evidence supporting the role of exercise in improving outcomes for patients with cancer. 

Exercise medicine is a subset of physical activity that is planned, structured, and repetitive, and aims to improve or maintain physical fitness and health or treat the disease. We believe that demonstrating the strong association between high levels of physical fitness—such as muscle strength and cardiorespiratory fitness—and lower mortality in patients with cancer will encourage both patients to advocate for exercise medicine and clinicians to prescribe it routinely.

How did the study go about this?

We performed a systematic review that included 42 prospective studies, for a total of approximately 47,000 patients with cancer. To comprehensively understand the association between physical fitness and mortality, we included studies on patients with any type or stage of cancer.

We specifically examined muscle strength and cardiorespiratory fitness, comparing high versus low levels and analyzing unit increments in these physical fitness components. In all studies, muscle strength was assessed using the handgrip strength test, a simple and cost-effective measurement, and low muscle strength was classified as <13 kg to <25.1 kg in women and <19.87 kg to <40.2 kg in men.

For cardiorespiratory fitness, studies used the 6-minute walking test and the cardiopulmonary exercise test, each with different thresholds (measured in meters walked or mL/kg/min) to distinguish high from low fitness levels.

Finally, the included studies tracked patients with cancer over time to examine all-cause mortality (death from any cause after a cancer diagnosis) and cancer-specific mortality (death directly caused by cancer).

What did the study find?

We found that patients with cancer with higher levels of physical fitness had a significantly reduced risk of mortality compared to those with lover levels. 

• Patients with higher muscle strength had a 31% lower risk of all-cause mortality compared to those with low muscle strength. Additionally, each increase in muscle strength was associated with an 11% further reduction in mortality risk.
• Patients with higher cardiorespiratory fitness had a 46% lower risk of all-cause mortality compared to those with low fitness levels. Notably, each unit increase in cardiorespiratory fitness was associated with an 18% lower risk of cancer-specific mortality.
• Importantly, higher muscle strength and cardiorespiratory fitness were particularly protective for patients with advanced cancer stage (reducing mortality risk by 8–46%), as well as for those with digestive (41%) and lung cancer (19–31%).

What are the key take-home points?

These findings make it clear that assessing muscle strength and cardiorespiratory fitness should become a routine part of cancer care, and any deficits in these areas should be addressed as a priority.

Indeed, higher physical fitness levels are strong predictors of survival in patients with any type of cancer and stage. Therefore, implementing tailored exercise prescriptions to enhance muscle strength and cardiorespiratory fitness throughout the cancer continuum could be employed to increase life expectancy.