High cardiorespiratory fitness levels may reduce cancer risk, mortality among men
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Key takeaways:
- Higher levels of cardiorespiratory fitness appeared associated with significantly lower risk for colon and lung cancers.
- Age had a modifying effect on the association of cardiorespiratory fitness and lung cancer.
Cardiorespiratory fitness levels appeared associated with cancer risk and mortality among a cohort of Swedish men, according to study results published in JAMA Network Open.
Researchers recommended prioritizing interventions to improve cardiorespiratory fitness among certain patient populations.
Rationale and methodology
Although previous research has investigated the association between physical activity and cancer risk, few studies have examined the influence of cardiorespiratory fitness on cancer risk, Elin Ekblom-Bak, PhD, researcher at The Swedish School of Sport and Health Sciences in Sweden, told Healio.
“Moreover, previous studies have typically only examined main effects and not investigated when in adulthood associations between cardiorespiratory fitness and cancer outcomes may be particularly strong or weak,” she said. “As increasing age is one of the strongest risk factors for several cancer types, and cardiorespiratory fitness levels tend to decline with older age, the associations between cardiorespiratory fitness and cancer incidence and mortality risk may vary depending on when in life cardiorespiratory fitness is assessed.”
Ekblom-Bak said the main barrier to investigating these associations is the need for large population samples.
“However, we are lucky to have access to a unique database of decades’ worth of occupational health assessments performed in the Swedish workforce,” she continued. “In combination with linkage of the data at an individual level using the unique Swedish personal identity number to the Swedish National In-hospital Registry and National Cause of Death Registry, we were able to retrieve data on first-time, cancer-specific events and mortality.”
The prospective cohort study included 177,709 men (mean age, 42 years; mean BMI, 26 kg/m2) in Sweden with completed occupational health assessment profiles between October 1982 and December 2019. Researchers examined cardiorespiratory fitness — defined as maximal oxygen consumption as milliliters per minute per kilogram — and incidence of and mortality due to prostate, colon and lung cancers among the study population. They additionally examined whether age moderated any associations between cardiorespiratory fitness and cancer.
Mean follow-up was 9.6 years.
Findings
Overall, researchers identified 1,918 incident cases of prostate cancer, 499 cases of colon cancer and 283 cases of lung cancer. They additionally observed 207 lung cancer deaths, 152 colon cancer deaths and 141 prostate cancer deaths.
Higher levels of cardiorespiratory fitness appeared associated with significantly lower risk for colon cancer (HR = 0.98; 95% CI, 0.96-0.98) and lung cancer (HR = 0.98; 95% CI, 0.96-0.99), but higher risk for prostate cancer (HR = 1.01; 95% CI, 1-1.01).
Results also showed an association between higher levels of cardiorespiratory fitness and lower risk for death among those with colon cancer (HR = 0.98; 95% CI, 0.96-1), lung cancer (HR = 0.97; 95% CI, 0.95-0.99) and prostate cancer (HR = 0.95; 95% CI, 0.93-0.97).
“We also observed a modifying effect of age on the association between cardiorespiratory fitness and lung cancer,” Ekblom-Bak said. “The lower risk with higher cardiorespiratory fitness for lung cancer incidence and death, even after adjustment for smoking, was evident only among those aged 60 years or older at the time of assessment. The takeaway from this is that when we aim to understand the relationship between cardiorespiratory fitness and cancer incidence and death, we need to take into consideration the age of individuals being tested.”
Implications
The findings highlight that higher cardiorespiratory fitness is not only important for reducing risk for cardiovascular disease, which is often communicated, but also for reducing cancer risk among men, Ekblom-Bak told Healio.
“Current cancer prevention guidelines focus on physical activity, but these findings show that cardiorespiratory fitness is also very important for both reducing cancer risk and mortality risk associated with common cancer types among men,” she said. “The importance of cardiorespiratory fitness could be included in future patient-physician discussions, and simple submaximal cycle tests could be included in health history assessments to better understand a person’s risk profile based on their lifestyle choices and health status. Men should be informed of the benefits of not only increasing their physical activity but also cardiorespiratory fitness and supported to find ways to improve their cardiorespiratory fitness in ways that feel best for them and avoid shaming the individual.”
Researchers are now examining a similar study among women, according to Ekblom-Bak.
“We are also conducting analyses to better understand a life course approach, which should provide a more nuanced understanding of the importance of cardiorespiratory fitness and cancer risk,” she said. “A large number of people in the current study returned for multiple health assessments; therefore, we have the rare opportunity to further understand how changes in cardiorespiratory fitness is associated with cancer risk.”
For more information:
Elin Ekblom-Bak, PhD, can be reached at elin.ekblombak@gih.se.
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