Some previous studies looking at the connection between physical activity and prostate cancer have been contradictory, according to Dr Kate Bolam, a co-author of the study. While some showed increased risk of prostate cancer for those who were physically active, others found a decreased risk.
But many of those studies had small sample sizes or were biased toward healthier people, said Dr Bolam, a researcher at the Swedish School of Sport and Health Sciences.
“Men who are generally more health-conscious,” she said, “are also good at going to the doctor when they are called for their prostate cancer screening tests.”
More testing means more diagnoses, including in men whose cancers will never progress. Sometimes cancer cells can exist in the prostate for one’s entire life and not be dangerous, so many men who are not tested and do not experience symptoms may never know they have prostate cancer.
The Swedish team was able to create a more nuanced picture by using a national database with hundreds of thousands of in-lab results, including fitness tests measuring how well the heart and the lungs supply oxygen to muscles.
Unlike with studies that rely on patients to report their exercise habits, this gave experts objective measurements. The results clearly showed a link between physical activity and a reduced prostate cancer risk. It also showed that greater improvements in fitness were associated with a greater reduction in risk.
This adds to a growing understanding of how important exercise is for prevention of cancer more generally. In 2019, a review by the American College of Sports Medicine found that regular physical activity significantly reduced the risk of bladder, breast, colon, endometrial, esophageal adenocarcinoma, kidney and stomach cancers.
The same analysis also found that having a regular exercise habit was tied to improved treatment outcomes and extended the life expectancies of those already living with cancer.