Men with cardiorespiratory fitness (CRF) who increased their CRF by more than 3% had a significantly lower risk of prostate cancer incidence, a large Swedish study found.
The prospective analysis, published in the British Journal of Sports Medicine, done in a cohort of nearly 58,000, was conducted by Kate A. Bolam, PhD, a clinical exercise physiologist at the Swedish School of Sport and Health Sciences in Stockholm.
“The findings suggest that physicians could work toward supporting patients to understand what types of activities could improve their fitness and ways they can incorporate these activities into their lives in an enjoyable way, or at the very least refer patients on to an exercise specialist,” Dr. Bolam said in an interview.
Grouped by baseline CRF, the association between change in absolute CRF and prostate cancer incidence was significant only for participants with a moderate baseline CRF. Moreover, changes in both absolute and relative CRF were not associated with prostate cancer mortality.
The lack of mortality significance may be due to the relatively few deaths from prostate cancer in the cohort, Dr. Bolam said. “It may be we weren’t powered to detect anything with such low numbers. And it’s not likely men will die from prostate cancer but more likely from more common chronic diseases such as heart disease.” The authors noted that unlike the case with other common cancers, there are relatively few preventable risk factors with strong evidence for reducing overall prostate cancer risk. “Aside from developmental factors, being diagnosed with overweight or obesity are the main risk factors for developing advanced prostate cancer, but insufficient evidence exists to extend this conclusion to non-advanced prostate cancer,” they wrote.
There is evidence, however, that exercise reduces all-cause mortality risk across many cancer types, including prostate.
Study details
The cohort was drawn from Swedish national health-profile database figures from 1982 to 2019. Participants completed an occupational health profile assessment including at least two valid CRF tests on a cycle ergometer. During a mean follow-up of 6.7 years, 592 (1%) of 57,652 men (mean age 41.3 years, standard deviation 10.55) were diagnosed with prostate cancer, and in 46 (.08%) prostate cancer was the primary cause of death.
An increase in absolute CRF (as a percentage of liters per minute of cardiac output) was associated with a reduced incidence risk, with a hazard ratio of 0.98 (95% CI, 0.96-0.99). Grouping participants as having increased (+3%), stable (±3%), or decreased (−3%) CRF, the investigators found increased fitness was associated with an HR for prostate cancer incidence of 0.65 (95% CI, 0.49-0.86), vs decreased fitness.
According to the authors, this and similar investigations of mechanisms behind physical activity benefits will lead to more targeted prevention recommendations. The results highlight the importance of encouraging the general public to increase CRF or reach moderate fitness levels, Dr. Bolam’s group wrote. The group is planning a similar study in breast cancer.
This study was funded by the Swedish Cancer Society. The authors declared no competing interests.