An increase in annual cardiorespiratory fitness may be linked to a lower risk of developing prostate cancer, according to a recent study published by Bolam et al in the British Journal of Sports Medicine.
Background
There are relatively few known risk factors for prostate cancer. Although research has shown that physical activity may reduce the risk of certain types of cancers, the association with prostate cancer is less understood.
Most previous studies have assessed fitness at only one time point—none of which have examined the potential impact of fitness on both the risk of developing and dying from prostate cancer.
Study Methods and Results
In the recent study, investigators used a national occupational health profile assessment database to identify 57,652 men who underwent at least two cardiorespiratory fitness tests measured by peddling on a stationary cycle—with the goal of determining whether improvements in cardiorespiratory fitness over time influenced the risk of prostate cancer incidence or mortality. Annual cardiorespiratory fitness measurements were expressed as absolute and relative VO2 max and divided into groups according to whether these increased by over 3%, decreased by over 3%, or remained stable each year. The investigators also assessed patients’ physical activity, lifestyle, perceived health, body mass index (BMI), and height data.
To evaluate whether changes in the risk of prostate cancer varied by baseline fitness, the investigators categorized patients into three equally sized groups based on low, moderate, and high levels of cardiorespiratory fitness.
For the incidence analysis, all of the study participants were monitored from the date of the last assessment to the date of their prostate cancer diagnosis or all-cause mortality, or until December 31, 2019.
For the mortality analysis, the participants’ survival was tracked from the date of their second assessment to the date of their prostate cancer mortality or all-cause mortality, or until December 31, 2019.
After an average follow-up of 7 years, about 1% of the participants (n = 592) were diagnosed with prostate cancer, and 0.08% (n = 46) of them died from the disease.
The investigators found that a 1% annual percentage increase in absolute cardiorespiratory fitness was associated with a 2% lower risk of prostate cancer, but not mortality, after accounting for potentially influential factors such as age, education level, year of testing, BMI, and smoking status.
When the participants were grouped according to whether their cardiorespiratory fitness had increased, decreased, remained stable, those whose fitness had improved by 3% or more per year were 35% less likely to develop prostate cancer compared with those whose fitness had decreased after accounting for potentially influential factors.
When the participants were grouped according to their cardiorespiratory fitness at their first assessment, the association between fitness and a reduction in the risk of prostate cancer was only statistically significant for those with a moderate level of baseline cardiorespiratory fitness—representing a 15% reduction in the risk of prostate cancer.
Conclusions
The investigators stressed that their study was observational and, as a result, was unable to establish causal factors. They further noted that genetic factors often have a major role in both an individual’s cardiorespiratory fitness and cancer risk.
“The results highlight the importance of [cardiorespiratory fitness] for prostate cancer risk, which has been challenging to determine with single time point studies,” the study authors underscored. “Improvements in [cardiorespiratory fitness] in adult men should be encouraged and may reduce the risk of prostate cancer,” they concluded.
Disclosure: For full disclosures of the study authors, visit bjsm.bmj.com.
