Effect of lifestyle factors on PSA and PSA velocity

Background: Smoking and obesity have been implicated in various carcinogenic processes. However, their role in prostate cancer (PCa) & their association with important biomarkers such as prostate specific antigen (PSA) & PSA velocity (rate of PSA) remains unresolved. This study investigates their association with PSA & PSA velocity (PSAV). Methods: Data were obtained from 699 men participating in a Phase 3 clinical trial aimed at investigating the effect of selenium supplementation on incidence of PCa. During the course of this trial 73 men were diagnosed with PCa. Results: As compared to non-smokers, smokers demonstrated statistically significant negative association with PSA (8.0 & 6.7ng/ml, p=0.02). This association was more pronounced in men diagnosed with PCa (14.7 & 9.9ng/ml) as compared to those not diagnosed with PCa (4.5 & 3.6ng/ml). As compared to non-obese subjects, obese subjects did not demonstrate a statistically significant association with PSA nor do these results change after stratifying the analysis by PCa status. Smoking was associated with statistically significant lower PSAV (p=0.008) whereas obesity was not. Using the standard PSA level of 4ng/ml as a cut off for conducting prostate biopsy, 14.6% of smokers in this study would not have been prescribed a prostate biopsy and thus misclassified as being negative for PCa. Conclusions: The negative association of smoking with PSA and PSA velocity could potentially be due to its negative effect on testosterone. Hence, increased vigilance may be warranted among smokers with borderline PSA to prevent the risk of delayed diagnosis and metastasis thus reducing morbidity and mortality associated with PCa.