PSA-Based Screening Outcomes, Dietary Heterocyclic Amine Exposure, and Prostate Cancer Risk in African Americans

Abstract : Prostate cancer (PC) is the second leading cause of male U.S. cancer deaths, with African-Americans having the highest rate of PC mortality worldwide, as well as more abnormal results from screening tests that correlate with current or eventual PC. A 5-year prospective NIH-funded clinic-based study investigated whether prostate-specific antigen (PSA) and digital rectal exam (DRE) screening indicators of PC risk in 500 African-American men 50 to 70 years of age who underwent PC screening in Oakland, CA (East Bay San Francisco area), were associated with estimated dietary exposures to 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which forms when meat is overcooked. The DOD-funded study expands that NIH-funded work by adding a new %-free-PSA test for 310 (108 from the NIH-funded study, plus 202 additional) men, results of which will be compared with PSA/ DRE results and PhIP exposures estimated by dietary interviews. For 392 men studied under the NIH protocol, an odds ratio (95% CL) of 32 (3.2, 720) for highly elevated PSA (?20 ng/mL) was observed in the highest 15% vs. the lower 50% of estimated daily PhIP intakes. As of 09-01-07, a total of 310 men completed participation using the expanded protocol, for a combined total of 702 men. For the final analysis of all 702 men, the corresponding OR was found to be 10 (2.9, 58). This study will help define the potential value of improved screening and dietary/behavioral intervention to reduce PC risk.