1. ¹Lawrence Livermore National Laboratory, Energy and Environment Directorate, University of California, Livermore, CA, USA
2. ²Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA
3. ³Alta Bates Summit Medical Center, Markstein Cancer Education and Prevention Center, Oakland, CA, USA

Correspondence: Dr KT Bogen, Lawrence Livermore National Laboratory, Energy and Environment Directorate L-396, University of California, 7000 East Avenue, Livermore, CA 94550-9900, USA. E-mail: bogen@LLNL.gov

Received 18 October 2006; Revised 6 December 2006; Accepted 6 December 2006; Published online 16 January 2007.

Abstract

African-American men die from prostate cancer (PC) nearly twice as often as white US men and consume about twice as much of the predominant US dietary heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a genotoxic rat-prostate carcinogen found primarily in well-cooked chicken and beef. To investigate the hypothesis that PhIP exposure increases PC risk, an ongoing prospective clinic-based study compared PC screening outcomes with survey-based estimates of dietary PhIP intake among 40–70-year-old African-American men with no prior PC in Oakland, CA. They completed food-frequency and meat-cooking/consumption questionnaires and had a prostate-specific antigen (PSA) test and digital-rectal exam. Results for 392 men indicated a 17 (17) ng/kg day mean (1 s.d.) daily intake of PhIP, about twice that of white US men of similar age. PhIP intake was attributable mostly to chicken (61%) and positively associated (R²=0.32, P<0.0001) with saturated fat intake. An odds ratio (95% confidence interval) of 31 (3.1–690) for highly elevated PSA 20 ng/ml was observed in the highest 15% vs lowest 50% of estimated daily PhIP intake (30 vs 10 ng/kg day) among men 50+ years old (P=0.0002 for trend) and remained significant after adjustment for self-reported family history of (brother or father) PC, saturated fat intake and total energy intake. PSA measures were higher in African-American men with positive family history (P=0.007 all men, P<0.0001 highest PSA quartile). These preliminary results are consistent with a positive association between PhIP intake and highly elevated PSA, supporting the hypothesis that dietary intervention may help reduce PC risk.