Increased levels of physical activity after a diagnosis of prostate cancer are associated with significantly better survival, according to the results of a new, large prospective cohort study (Friedenreich CM, et al. Eur Urol. 2016 Jan 7. Epub ahead of print).
Men with the highest self-reported levels of physical activity had a >40% reduction in the risk for overall mortality from prostate cancer. High levels of recreational activity were associated with a similar reduction in prostate cancer–specific mortality.
Higher sustained levels of recreational activity before and after a prostate cancer diagnosis predicted lower all-cause mortality, suggest Christine M. Friedenreich, PhD, Scientific Leader of Cancer Epidemiology and Prevention Research, Alberta Health Services, Calgary, Canada, and colleagues.
“The big news here is that physical activity post-diagnosis improves survival….This paper is a good news story for men who have been diagnosed with prostate cancer since increasing their levels of activity after diagnosis can improve their survival,” said Dr Friedenreich.
Modifiable Risk Factors
Despite the large number of men affected by prostate cancer annually, potentially modifiable risk factors have received relatively little attention in the literature. Many recent studies have focused on dietary factors and obesity, and their potential contributions to prostate cancer risk. By comparison, the association between physical activity and prostate cancer has received little attention, particularly the impact of physical activity on the mortality of men with this disease, according to Dr Friedenreich and colleagues.
To examine physical activity and mortality in patients with prostate cancer, the investigators analyzed self-reported data provided by 830 men newly diagnosed with stage II to stage IV prostate cancer between 1997 and 2000. Each man reported his estimated activity level at diagnosis and at as many as 3 follow-up visits after diagnosis. The self-reported information was converted into the annual amount of metabolic equivalents (METs) of activity weekly. (A MET is defined as the ratio of the energy rate expended during an activity to the energy rate expended at rest.)
All participants survived at least 2 years after diagnosis, and the cohort had a maximum follow-up of 17 years. During follow-up, 458 of the patients died, of whom 170 men died from prostate cancer. In addition, 239 of the patients had disease recurrence or progression after the first follow-up visit.
Significant Impact of Physical Activity
Comparing self-reported physical activity and prostate cancer mortality, the investigators found that men who had a postdiagnosis activity level of >119 METs (ie, the highest activity category) had a lower mortality risk than men whose activity level was ≤42 METs (ie, the lowest category), a significant difference (hazard ratio [HR], 0.58; P <.01).
A separate analysis that focused specifically on recreational activity, defined as any exercise or sport performed standing up, yielded a similar difference for prostate cancer–specific mortality. The analysis showed that men in the highest category of recreational activity (≥26 METs) had a significantly lower mortality risk from prostate cancer than men who reported the least recreational activity (≤4 METs; HR, 0.56; P <.01).
An analysis of physical activity before and after receiving a diagnosis of prostate cancer yielded a significant reduction in all-cause mortality for men who maintained high levels of recreational activity versus men with the least recreational activity. Men who had sustained recreational activity of >18 to 20 METs had a lower risk for all-cause mortality than men who had sustained recreational activity of less than 7 to 8 METs (HR, 0.66).
“These findings support emerging recommendations to increase physical activity after the diagnosis of PCa [prostate cancer] and would inform a future exercise intervention training examining PCa outcomes,” the investigators noted.