21 Apr Prostate Cancer Mortality May Be Reduced By Moderate Physical Activity
MedicalResearch.com Interview with:
Ying Wang, PHD | Senior Epidemiologist
American Cancer Society, Inc.
250 Williams St.
Atlanta, GA 30303
MedicalResearch.com: What is the background for this study?
Dr. Wang: Although evidence is still limited, previous studies suggest that vigorous activity and brisk walking after prostate cancer diagnosis might be associated with lower risk of prostate cancer progression and disease-specific mortality. We still don’t know if physical activity before diagnosis is associated with the risk or not. This is also important because reverse causation is a concern in the analysis of post-diagnosis physical activity, especially for vigorous activity, that men with advanced diseases may reduce their activity level. In contrast, pre-diagnosis physical activity is less subject to reverse causation and may represent a long-term behavior. When walking, the most common type of physical activity, was examined separately in previous studies, it was not evaluated in the absence of other activities. No study has examined sitting time in relation to mortality among prostate cancer survivors, although previous study suggests longer sitting time is associated with higher risk of all-cause mortality in healthy populations. So in our study, we aimed to examine physical activity, walking only, and sitting time both before and after diagnosis in relation to prostate cancer-specific mortality.
MedicalResearch.com: What are the main findings?
Dr. Wang: We found that men who engaged in higher physical activity levels (equivalent to at least twice of the minimum physical activity recommendations) after diagnosis had a significantly lower risk of dying from prostate cancer, compared with the least active men. Similarly, significantly reduced risk was seen in men with higher physical activity levels before diagnosis, which suggests that the inverse association we saw with post-diagnosis physical activity was not purely due to reverse causation.
We were able to evaluate walking only in the absence of other activities, because about 40 percent of patients in the study reported that walking was the only form of recreational physical activity they did. Walking for four to six hours per week before diagnosis was associated with a substantially lower risk of prostate cancer-specific mortality, and men who walked seven or more hours per week had a greater reduced risk. No statistically significant association was observed with walking after diagnosis, or leisure time spent sitting assessed either before or after diagnosis.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Wang: The American Cancer Society recommends cancer survivors engage in a minimum of 150 min of moderate-intensity or 75 min of vigorous-intensity physical activity per week. Our study support that prostate cancer survivors should adhere to this guideline for better survival. Physicians should consider to promote a physical activity lifestyle to their prostate caner patients.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Wang: Future studies should examine biomarkers in blood or tumor tissues to better understand biological mechanisms of the effect of physical activity on prostate cancer progression.
MedicalResearch.com: Is there anything else you would like to add?
Dr. Wang: The analysis included over 10,000 prostate cancer survivors diagnosed with non-metastatic prostate cancer between 1992 and 2011 in the Cancer Prevention Study II Nutrition Cohort. It is so far the largest study that examined physical activity and prostate cancer survival among prostate cancer survivors.
Citation: Abstract presented at the April 2016 AACR meeting
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