Shorter CAG repeats in androgen receptor and non-GG genotypes in prostate-specific antigen loci are associated with decreased risk of benign prostatic hyperplasia and prostate cancer

The age-adjusted risk of prostate cancer (PC) has increased in Singapore since 1968. We investigated the relationship between polymorphisms in four genes, androgen receptor (AR), prostate-specific antigen (PSA), 5α-reductase type II (SRD5A2) and cytochrome P450c17α (CYP17) and PC and benign prostatic hyperplasia (BPH). Men with shorter CAG repeats in AR and above 69 years at diagnosis showed a trend of decreased PC risk (OR = 0.28, 95% CI = 0.08–1.03; p = 0.05). Shorter CAG repeats and non-GG genotypes in the AR and PSA loci, respectively, showed a trend of decreased PC risk (OR = 0.25, 95% CI = 0.06–1.03; p = 0.06) and a significantly decreased BPH risk (OR = 0.38, 95% CI = 0.15–0.94; p = 0.04).The results indicate that allelic variation in PSA promoter activity may be androgen dependent and interaction of genes in androgen pathway may influence the risk of BPH and PC in Singapore males.