In recent years, one of the most provocative questions in cancer research has been whether regular physical activity can prevent the onset of certain cancers.
The answer, as with any cancer-related question, is complicated. But a recent study published in the British Journal of Sports Medicine provided insight into how regular physical activity affects the risk of prostate cancer, the second most common and second most deadly cancer in the United States. men.
In one of the largest efforts of its kind to date, researchers collected data between 1982 and 2019 from 57,652 Swedish men who had participated in at least two fitness tests to see if those who were more active were less likely to develop cancer. About 1% were later diagnosed with prostate cancer. The team found that those whose physical condition had improved over the years were 35% less likely to have been diagnosed with the disease.
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This finding is consistent with much of the latest research on the relationship between physical fitness and cancer diagnosis. According to a 2021 study, for example, if all adults in the United States met physical activity guidelines, cancer diagnoses could decrease by 3%, or 46,000 cases, each year.
But while extensive research has been done on the relationship between exercise and diseases such as breast cancer, there has been less research specifically on prostate cancer. The risk of having prostate cancer increases for all men after age 50; the risk seems to run in families. About 1 in 8 men will be diagnosed with prostate cancer in their lifetime, according to the American Cancer Society.
Some previous studies looking at the link between physical activity and prostate cancer have been contradictory, according to Dr. Kate Bolam, co-author of the study. While some showed an increased risk of prostate cancer in those who were physically active, others found a decreased risk.
But many of these studies had small sample sizes or were biased toward healthier people, said 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 screenings.”
More tests mean more diagnoses, including in men whose cancer will never progress. Sometimes cancer cells can exist in the prostate for life without being dangerous. This is why many men who don’t get tested and have no symptoms may never know they have prostate cancer.
The Swedish team was able to create a more nuanced picture by using a national database containing hundreds of thousands of laboratory results, including fitness tests measuring how well the heart and lungs supply oxygen to the muscles .
Unlike 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 risk of prostate cancer. It also showed that greater improvement in fitness was associated with greater risk reduction.
This adds to a growing understanding of the importance of exercise for cancer prevention more generally. In 2019, a study from the American College of Sports Medicine found that regular physical activity significantly reduced the risk of cancers of the bladder, breast, colon, endometrial, esophagus, kidney and of the stomach. The same analysis also found that having a regular exercise habit was linked to better treatment outcomes and an extended life expectancy for people who already had cancer.
Although it’s unclear exactly how this happens, experts said one explanation could be that exercise helps fight cancer by improving the way the immune system targets and eradicates cancer cells.
“We know that even a single bout of exercise helps our bodies release immune cells into our circulation,” said Neil M. Iyengar, a medical oncologist and physician scientist at Memorial Sloan Kettering Cancer Center in New York, who not participated in the study. “It also helps improve the population of immune cells in our tissues that fight cancer cells.”
He added: “In someone who exercises, you see more immune cells that are actually capable of killing cancer cells. Whereas for someone who is more sedentary, especially obese, we see the opposite.
Researchers don’t yet know exactly the right dose or type of exercise that might be most effective, but the American Cancer Society and American Society of Clinical Oncology recommend 150 minutes per week, or 20 minutes per day, d aerobic exercise. This could be light walking, jogging, or weight-bearing exercises.
Iyengar and Bolam recommend starting simple: find an enjoyable activity and get moving. This might include playing with your children or grandchildren, going for a walk, or joining a recreational sports league. Consistency is key, they say, which is why it’s important to find an activity that doesn’t feel like a chore.
“Everyone has an opportunity to do something really cost-effective here to reduce their risk of prostate cancer,” Bolam said. “And that’s something that’s entirely within our control.”
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