Prostate cancer is a leading solid tumor among men in the Western world. Androgens play an important role in the carcinogenesis and treatment of prostate cancer. CYP3A5 is a cytochrome P450 superfamily member which also has activity in testosterone metabolism. In this study, we looked for two-gene interactions associated with clinical characteristics of prostate cancer in the Finnish population. We used multifactor-dimensionality reduction for the identification of the two-gene interactions in androgen metabolism pathway genes together with clinical characteristics of prostate cancer among 754 genotyped prostate cancer patients. The CYP3A5*3/*3 and SRD5A2 A49T GG genotype interaction was associated with the clinical tumor stage T2-T4 (T-stage, TNM classification) with odds ratio (OR) 2.14, 95% confidence interval (CI) 1.35-3.40. Patients with CYP3A5*3/*3 and KLK3 I179T CC/TC genotypes had increased OR 2.30, 95% CI 1.16-4.58 for metastatic disease. Further, two-gene interaction CYP3A5*3/*3 and KLK3 -252A > G AA was associated with Gleason scores >or=7 with OR 1.52, 95% CI 1.11-2.09. Prostate cancer patients with CYP3A5*3/*3 and KLK -252A > G GG/AG genotypes had decreased OR of 0.70 with 95% CI 0.50-0.98 for high prostate-specific antigen levels at diagnosis. For prostate cancer patients aged below 65 years, the OR for interaction of CYP3A5*1/*3 or *1/*1 and AKR1C3 Q5H CC genotypes was 1.84 with 95% CI 1.03-3.28. For prostate cancer, the best two-gene interaction included genotypes SRD5A2 V89L GG and AKR1C3 Q5H CC with OR 1.30, 95% CI 1.01-1.66. It remains to be clarified whether these polymorphism associations identified here are also present in other populations.
(c) 2008 Wiley-Liss, Inc.