Pre-diagnostic circulating sex hormone levels and risk of prostate cancer by TMPRSS2:ERG status.

Abstract

93 Background: Experimental studies have shown that androgen receptor stimulation can facilitate formation of the TMPRSS2:ERG gene fusion in prostate cell lines. No study has tested whether higher pre-diagnostic circulating sex hormone levels in men increase the risk of developing TMPRSS2:ERG positive prostate cancer specifically. Methods: We conducted a nested case-control study of 200 prostate cancer cases and 1,057 controls from the Physicians’ Health Study and Health Professionals Follow-up Study. We examined associations between pre-diagnostic circulating levels of total testosterone, free testosterone, DHT, androstanediol glucuronide, estradiol, and SHBG and risk of prostate cancer by TMPRSS2:ERG status. TMPRSS2:ERG was assessed by ERG immunohistochemistry. We used multivariable unconditional polytomous logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for risk of fusion-positive (n = 94) and, separately, fusion-negative (n = 106) disease. Results: Free testosterone was significantly associated with the risk of ERG-positive prostate cancer (OR: 1.37, 95% CI: 1.05-1.77), but not ERG-negative prostate cancer (OR: 1.09, 95% CI: 0.86-1.38) (p-diff: 0.17). None of the remaining hormones evaluated showed clear differential associations with ERG-positive versus ERG-negative disease. Conclusions: These findings provide some suggestive evidence that higher pre-diagnostic free testosterone levels are associated with an increased risk of developing TMPRSS2:ERG positive prostate cancer but are not associated with prostate cancer that lacks TMPRSS2:ERG.