Physical activity and prostate cancer risk reduction: Does race matter?

235 Background: We previously reported that physical activity may reduce prostate cancer (CaP) risk among men undergoing prostate biopsy. However, whether the potential benefit of exercise against cancer differs by race is unclear. We therefore sought to further characterize the link between physical activity and CaP risk as a function of race. Methods: Men undergoing prostate biopsy at the Durham VA Hospital were asked to complete a survey assessment of current exercise habits including frequency of differing intensities (mild, moderate and strenuous) as well as the average duration. Total current exercise was calculated by multiplying the frequency of sessions within each intensity by their average duration, weighted by the estimated metabolic equivalent (MET) and then summed across all intensities expressed as average total MET hrs/wk. Specifically, exercise intensities were as follows: mild (3 METs, e.g. easy walking), moderate (5 METs, e.g. tennis), and strenuous (9 METs, e.g. running). Quantified exercise was compared between race groups using rank sum test. Associations between exercise and CaP risk was determined using crude and adjusted logistic regression stratified by race. Results: A total of 308 men had complete data for analysis. Of these men, 53% were white and 47% were black. There was no significant difference in the amount of physical activity between race groups (p= 0.11). Increased amount of exercise was associated with decreased CaP risk for white men in both crude (OR= 0.89; 95% CI=0.81–0.98; p=0.02) and adjusted (OR=0.90; 95% CI=0.82−0.99; p=0.04) regression models that controlled for age, BMI, DRE, previous biopsy, and family history of CaP. We found no association between exercise and CaP risk among black men in both crude (p=0.79) and adjusted regression models (p=0.87). Conclusions: Increased physical activity was associated with CaP risk reduction among white men but not among black men. Further investigations to validate this potential source of CaP race disparity and to identify exercise-specific parameters that influence CaP risk reduction (ex. age-specific or cumulative exercise) are required. Investigating the race-specific mechanisms through which exercise modifies CaP risk is also warranted.