CYP1A1, CYP3A5 and CYP3A7 polymorphisms and testicular cancer susceptibility

Abstract

Testicular cancer (TC) incidence is increasing worldwide, but the aetiology remains largely unknown. An unbalanced level of oestrogens and androgens in utero is hypothesized to influence TC risk. Polymorphisms in genes encoding cytochrome P450 (CYP) enzymes involved in metabolism of reproductive hormones, such as CYP1A1, CYP3A5 and CYP3A7, may contribute to variability of an individual's susceptibility to TC. The aim of this case-control study was to investigate possible associations between different CYP genotypes and TC, as well as histological type of TC. The study comprised 652 TC cases and 199 controls of Norwegian Caucasian origin. Genotyping of the CYP1A1*2A (MspI), CYP1A1*2C (I462V), CYP1A1*4 (T461N), CYP3A5*3C (A6986G) and CYP3A7*2 (T409R) polymorphisms was performed using TaqMan allelic discrimination or sequencing. The CYP1A1*2A allele was associated with 44% reduced risk of TC with each polymorphic allele [odds ratio (OR) = 0.56, 95% confidence interval (CI) = 0.40-0.78, p(trend) = 0.001], whereas the CYP1A1*2C allele was associated with 56% reduced risk of TC with each polymorphic allele (OR = 0.44, 95% CI = 0.25-0.75, p(trend) = 0.003). The decreased risk per allele was significant for seminomas (OR = 0.46, 95% CI, 0.31-0.70, p(trend) < 0.001 and OR = 0.31, 95% CI = 0.14-0.66, p(trend) = 0.002, respectively), but only borderline significant for non-seminomas (OR = 0.65, 95% CI = 0.45-0.95, p(trend) = 0.027 and OR = 0.55, 95% CI = 0.30-1.01, p(trend) = 0.052, respectively). There were no statistically significant differences in the distribution of the CYP3A5*3C and CYP3A7*2 polymorphic alleles between TC cases and controls. This study suggests that polymorphisms in the CYP1A1 gene may contribute to variability of individual susceptibility to TC.