Cardiorespiratory Fitness Linked to Lower Cancer Incidence and Mortality

Research published in JAMA Network Open indicates that cardiorespiratory fitness may be associated with a lower risk of colon cancer incidence and a lower risk of death from lung and prostate cancer in men, highlighting the potential role of fitness in reducing cancer risk and mortality. 

This prospective cohort study aims to investigate the association between midlife cardiorespiratory fitness (CRF) and colon, lung, and prostate cancer incidence and mortality in men, while also analyzing any moderation of the associations by age. 

Data was collected from the health profile assessment (HPA) database managed by the HPI Health Profile Institute in Stockholm, Sweden. Since the 1970s, health profile assessments have been conducted in Swedish health services, with the results stored in a central database since 1982. The study included 180,764 men aged 18-75 years with a first-time HPA and valid estimate of cardiorespiratory fitness (CRF), with 177,709 men included in the analysis after excluding records with missing covariate data and individuals already diagnosed with certain cancers. 

To assess cardiorespiratory fitness, the standardized Åstrand cycle ergometer test was used to estimate maximal oxygen consumption. Participants were instructed to abstain from vigorous physical activity, heavy meals, smoking/snuff use, and stress before the test. Previous validation studies have shown comparable results between estimated and directly measured maximal oxygen consumption, with small mean differences and similar error rates.  

To track cancer incidence and mortality, data was retrieved from the Swedish National Patient Registry and National Cause of Death Registry. Individual-level analyses were conducted by linking study data to unique personal identity numbers. Participants were followed up from their health promotion assessment to the first cancer-specific event or death, using specific International Statistical Classification of Diseases and Related Health Problems codes for colon, lung, and prostate cancer. 

Various covariates were assessed based on evidence of their influence on cancer and mortality. These included educational attainment, smoking, diet, alcohol habits, body mass index, and comorbidities. Data was obtained from Statistics Sweden, self-report statements, physical measurements, and the Swedish National Patient Registry. Covariate scores were calculated based on the presence of hypertension, cardiovascular disease, diabetes, and other cancers. 

Data analysis was conducted from June 22, 2022 to May 11, 2023 using general linear modeling and Cox proportional hazards regression models. The analysis compared estimated V̇o2max between incident and mortality cases and noncases, as well as the outcomes of colon, lung, and prostate cancer incidence and death. Three models were used, adjusting for different variables such as age, BMI, education, smoking, diet habits, and comorbidity, to evaluate the associations between CRF and the outcomes. 

Data was analyzed on 177,709 men between the ages of 18 and 75 years, with an average age of 42 and an average body mass index of 26. Over an average follow-up period of 9.6 years, there were 499 cases of colon cancer, 283 cases of lung cancer, and 1918 cases of prostate cancer, as well as 152 deaths due to colon cancer, 207 deaths due to lung cancer, and 141 deaths due to prostate cancer. The study found that higher levels of maximal oxygen consumption were associated with a lower risk of colon and lung cancer incidence, but a higher risk of prostate cancer incidence. Additionally, higher levels of maximal oxygen consumption were associated with a lower risk of death due to colon, lung, and prostate cancer. The associations between maximal oxygen consumption and cancer incidence and mortality remained significant even after adjusting for various factors. Age also had a modifying effect on the associations for lung and prostate cancer incidence, as well as for death due to lung cancer. 

“If these findings can be supported with randomized clinical trials, CRF appears to have a potentially important role in reducing the risk of developing and dying from certain common cancers in men,” said researchers. “Future research should consider examining exposures at different times in the life course and the associations between CRF and cancer incidence and mortality.” 

Reference 

Ekblom-Bak E, Bojsen-Møller E, Wallin P, et al. Association between cardiorespiratory fitness and cancer incidence and cancer-specific mortality of colon, lung, and prostate cancer among Swedish men. JAMA Netw Open. 2023;6(6):e2321102. doi:10.1001/jamanetworkopen.2023.21102