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.