Earlier research has linked vigorous physical exercise with a lower risk of death from prostate cancer. This new study found that moderate levels of exercise are also associated with a reduced risk of prostate cancer death.
Researchers evaluated data from 10,067 men who had been diagnosed with non-metastatic prostate cancer between 1992 and 2011. The men were between 50 to 93 years old at the time of diagnosis. During the study period, 600 men died of prostate cancer. The data came from the Cancer Prevention Study II Nutrition Cohort.
The men in the study reported the amount of time they spent exercising and the amount of time they spent sitting. Physical activity included walking, dancing, bicycling, jogging or running, doing aerobics, swimming laps, and playing tennis or racquetball. Based on the men’s reporting, the researchers calculated metabolic equivalent (MET) hours per week of activity.
The researchers evaluated the hours of exercise for men both before and after they were diagnosed with prostate cancer. Men who exercised for 17.5 or more MET hours per week before being diagnosed with cancer had a 30% lower risk of prostate cancer mortality than men who exercised for fewer than 3.5 MET hours per week (equivalent to less than 1 hour of moderate walking per week).
The study also found that men who exercised the most after their diagnosis had a 34% lower risk of dying from prostate cancer when compared to men who exercised the least. Patients who exercised after being diagnosed benefited from maintaining physical activity even if they hadn’t exercised before having cancer.
Sitting time, which included time sitting or driving in vehicles, watching TV and reading was not associated with prostate cancer mortality.
“The American Cancer Society recommends adults engage in a minimum of 150 minutes of moderate or 75 minutes of vigorous physical activity per week. These results indicate that following these guidelines might be associated with better prognosis,” said lead author Ying Wang, PhD, senior epidemiologist in the Epidemiology Research Program at the American Cancer Society in Atlanta.
Almost 40% of patients in the study reported walking as their only form of physical activity. In the study, walking for 4-6 hours per week before diagnosis was associated with a 33% lower risk of prostate cancer death. Walking for 7 or more hours per week before diagnosis was associated with a 37% lower risk of prostate cancer death. The researchers did not observe a statistically significant association with walking after diagnosis.
A limitation of the study was the subjects reporting their own physical activity and sitting time data, which is subject to errors in reporting.
The findings were presented at the annual meeting of the American Association for Cancer Research (AACR), which took place April 16-20, 2016 in New Orleans.