In a recently published study, Dr British Journal of Sports Medicine, Researchers are investigating the relationship between changes in cardiorespiratory fitness (CRF) and prostate cancer incidence and mortality in adults.
Study: Relationship between cardiorespiratory fitness and prostate cancer incidence and mortality in 57,652 Swedish men.. Image credit: Peakstock / Shutterstock.com
Unlike other cancers, such as those affecting the breast, colon, and lung, where preventable risk factors are well established, it remains unclear which factors increase a person’s risk of prostate cancer. Early known risks include developmental factors and being overweight or obese, especially for advanced prostate cancer; However, evidence for non-advanced cases is limited.
Although physical activity affects many types of cancer, its effect on prostate cancer remains clear, with studies showing mixed results. CRF, which is associated with lower systemic inflammation and improved health markers, has been less explored in prostate cancer research. Conflicting results between CRF and physical activity studies, potentially influenced by higher screening rates among fitter individuals, emphasize the need for additional studies.
About the study
The researchers analyzed data from the Health Profile Assessment (HPA) database managed by the Health Profile Institute in Stockholm, Sweden. The HPA, offered at no cost to employees of the respective companies, included lifestyle questionnaires and a submaximal ergometer CRF test.
CRF was measured using the validated Åstrand test, and participants were classified into groups based on a greater than 3% change in absolute CRF. Prostate cancer incidence and mortality data were obtained from the Swedish National Health Registry linked to the HPA database.
Statistical analysis involved Cox proportional hazards regression models to examine the association between CRF changes and prostate cancer. The researchers adjusted for factors such as age, body mass index (BMI) and smoking. Sensitivity analysis was conducted to mitigate reverse causality concerns.
All analyzes followed established statistical evaluation guidelines and were performed using R Studio and associated packages.
Between 1982 and 2019, data were acquired from 181,673 men, of whom 58,971 met the criteria of having two or more CRF tests with a minimum interval of 11 months between tests.
After excluding 1,319 individuals for extreme CRF variation, the sample consisted of 57,652 men with a mean age of 41.4 years and a mean BMI of 26.0 kg/m.2. Of these men, 592, or 1% of the study group, developed prostate cancer, of whom 46 died of the disease.
At baseline, absolute and mean relative CRF values were 3.12 L/min and 37.4 mL/kg/min, respectively. There was little reduction in both relative and absolute CRF over an average of 4.9 years between trials. The follow-up period for the incidence analysis averaged 6.7 years from the last CRF examination.
No association between baseline or end-exam CRF and prostate cancer risk was observed after adjustment for factors such as age, BMI, and smoking status. However, in unadjusted analyses, higher CRF at both time points was inversely associated with prostate cancer risk.
Notably, absolute CRF reduction was associated with a higher risk of prostate cancer diagnosis. This association remained significant after adjusting for all covariates, including physical activity.
They were also categorized by CRF participant change, which included increase, stable or decrease +3%, ±3% and −3%, respectively. Those with increased CRF had a significantly lower risk of cancer compared to the stable group, which was consistent in most adjusted models.
A sensitivity analysis confirmed the significance of full CRF variation in cancer risk excluding early diagnosis after the last examination. However, significant variability was observed across models when comparing stable CRF with increased or decreased groups.
Subgroup analysis, which was stratified by baseline CRF level, revealed that in the median baseline CRF group of 32.4–40.7 mL/kg/min, each standard deviation increase in absolute CRF reduced prostate cancer risk by 16% in the least adjusted model, more adjusted with significant associations persisting in the models. In comparison, the low and high fitness groups showed no significant relationship except for an inverse relationship in the high fitness group in the minimally adjusted model, which decreased after further adjustment.
A positive correlation was also observed between absolute CRF and change in self-reported physical activity. However, changes in CRF were not associated with prostate cancer mortality, as observed in 46 men who died in the study.
- Bolam, K. A., Bojsen-Möller, E., Wallin, P., etc (2024). Relationship between cardiorespiratory fitness and prostate cancer incidence and mortality in 57 652 Swedish men. British Journal of Sports Medicine. doi:10.1136/bjsports-2023-107007