Clinically occult prostate cancer cases may distort the effect of testosterone replacement therapy on risk of PCa

Background Although prostate cancer (PCa) screening is conducted before testosterone replacement therapy (TRT), clinically occult PCa cases may exist. Methods To evaluate whether the possible inclusion of occult PCa cases distorts the effect of TRT on risk of PCa, we followed 776 hypogonadal males (TRT = 400, non-TRT = 376) from a urology center in Germany from 2004 to 2016, with a mean follow-up period of 7 years. We assumed occult cases might take 1-2 years (latency period) to become clinically detectable after receiving TRT. We selected several latency periods (12/18/24 months) and compared the risk of PCa in the TRT and non-TRT group over the latency period, from the end of latency period till the end of follow-up, and over the whole follow-up time. Results Overall, 26 PCa cases occurred in the non-TRT group vs 9 cases in the TRT group. Within 18 months of follow-up, 9 cases occurred in the TRT group vs 0 cases in the non-TRT group; from the end of 18 months till the end of follow-up, 26 cases occurred in the non-TRT group vs 0 cases in the TRT group. The adjusted table showed seemingly adverse effects of TRT on PCa development within 18 months (p = 0.0301) and beneficial effects from the end of 18 months till the end of follow-up (p = 0.0069). Similar patterns were observed for 12 or 24 months as the latency period. Conclusions TRT may make occult PCa cases detectable within early phase of treatment and present a beneficial effect in the long run. Future longitudinal studies are needed to confirm findings from our exploratory analyses.