Muscle strength, cardiorespiratory fitness linked to lower mortality for those with cancer
Key takeaways:
- High muscle strength and cardiorespiratory fitness reduced risk for death among people with cancer.
- Increased muscle strength reduced mortality risk for those with advanced cancer.
High muscle strength and cardiorespiratory fitness reduced mortality for people diagnosed with cancer, according to a systematic review and meta-analysis.
High muscle strength significantly decreased mortality for those with advanced cancers, as well.
“It is clear from these findings that the assessment of muscle strength and cardiorespiratory fitness should be part of routine care for people with cancer, and that any deficits in these parameters should be addressed as priority with targeted exercise medicine prescription to reduce the risk for death of any cause,” Francesco Bettariga, BSc (honor), MSc (honor), PhD candidate in exercise oncology at Exercise Medicine Research Institute at Edith Cowan University in Australia, told Healio.
Background and methods
More than 2 million individuals in the U.S. will be diagnosed with cancer this year, and more than 600,000 will die of the disease, according to an American Cancer Society annual report.
Improved screening and treatment have reduced mortality, but treatment-related adverse events, physical inactivity and elevated body weight can increase risk for death.
Previous research showed increased muscle strength and cardiorespiratory fitness lowered risk for all-cause, cardiovascular and pulmonary disease mortality among healthy adults. However, their impact on individuals who already have cancer had not been defined.
“Even though exercise has been proven to greatly improve quality of life, physical function and body composition, exercise medicine is still not considered an essential component of care for patients with cancer,” Bettariga said. “In addition, it is yet to be proven if higher physical fitness levels are associated with reduced mortality in people already diagnosed with cancer. We believe that by demonstrating that certain types of exercise actually are associated with improved survival will be a strong motivator for patients to demand exercise medicine and clinicians to routinely describe it.”
Bettariga and colleagues used PubMed, CINAHL, SPORTDiscus, Web of Science and Embase databases to investigate.
They identified 1,903 potential studies, considered 182 for full-text assessment and included 42 in the meta-analysis.
Studies classified low muscle strength as hand grip strength between less than 13 kg to less than 25.1 kg for women, and less than 19.87 kg to less than 40.2 kg for men.
Studies classified low cardiorespiratory fitness using both cardiopulmonary exercise and 6-minute walking tests.
The impact muscle strength and cardiorespiratory fitness had on all-cause and cancer-specific mortality for people diagnosed with cancer served as the primary endpoint.
Results and next steps
The 42 studies included 46,694 adults with cancer (median age, 64 years; interquartile range, 58.8-70.5; median BMI, 24.8 kg/m²; interquartile range, 22.7-26.6).
People with high muscle strength had a 31% reduced risk for all-cause mortality compared with those who had low strength (HR = 0.69; 95% CI, 0.61-0.78).
In multivariable models, researchers observed a significant association between high muscle strength and decreased mortality for individuals with advanced cancers (range of risk reduction, 23% to 46%; P < .001) but not those with early-stage disease.
“We were pleasantly surprised with the result,” Bettariga said.
Unit increments in muscle strength reduced risk for all-cause mortality by 11% (HR = 0.89; 95% CI, 0.82-0.97), as well.
Bettariga and colleagues also found high muscle strength to be associated with reduced mortality due to digestive cancer (HR = 0.59; 95% CI, 0.38-0.94) and lung cancer (HR = 0.81; 95% CI, 0.73-0.9).
Patients with high cardiorespiratory fitness had a 46% lower risk for all-cause mortality than those who had low levels (HR = 0.54; 95% CI, 0.38-0.84).
Superior cardiorespiratory fitness appeared linked with significantly lower all-cause mortality among people with lung cancer by 31% (HR = 0.69; 95% CI, 0.5-0.96).
Unit increments in cardiorespiratory fitness reduced risk for cancer-specific mortality by 18% (HR = 0.82; 95% CI, 0.69-0.98).
“Our findings can be of relevance for all people diagnosed with cancer,” Bettariga said. “This emphasizes, again, how exercise is not only safe for patients with cancer, but also induces significant benefits, including a reduced mortality risk.”
Researchers acknowledged study limitations, including the use English-language studies and prospective studies only, which investigators said “limits determining causality of physical fitness changes after cancer-related treatment or side effects on all-cause and cancer-specific mortality.”
“There is now an urgent need for research into the underlying biological mechanisms by which exercise acts as an anti-cancer medicine,” Bettariga said. “Once these mechanisms are better understood, we can then prescribe exercise medicine more precisely, producing greater treatment effects against the cancer whilst minimizing the time and effort required by the patient to undertake their exercise medicine.”
For more information:
Francesco Bettariga, BSc (honor), MSc (honor), can be reached at francescobettariga@gmail.com.
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