BERKELEY, CA (UroToday.com) - Our study arises from our interest in finding predictors of disease reclassification in men on AS, as it is known that approximately a third of these men will progress and require active treatment. We assessed the use of serum total testosterone and free testosterone as predictors of disease reclassification in a cohort of men on AS at our institution. Our results suggest low levels of testosterone are associated with more aggressive prostate cancer. This contradicts long-held beliefs that high testosterone is risky for prostate cancer, and low testosterone is protective.
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We used receiver–operator curves to identify the best cut-off of free testosterone level and found 0.45 ng/dL as the most appropriate threshold for further analyses. Men with free testosterone levels lower than this value had a fourfold higher risk of disease reclassification compared with men with higher free testosterone values. Reclassification was noted in 9 of 13 men with free testosterone levels < 0.45 ng/dL compared with 36 cases of disease reclassification among 98 men with free testosterone levels > 0.45 ng/dL (P = 0.035). The associated OR was 4.3 (CI 1.2547–14.7372). Our cohort of men undergoing AS was fairly small, and data regarding total testosterone and free testosterone were available for most, but not all men, reducing statistical power. We need new studies with larger populations to validate our proposed threshold. In borderline cases, the presence of low values of free testosterone may help determine whether it is more prudent to initiate treatment rather than continue observation. Whether low serum-free testosterone levels may have biological implications in PCa progression in men with early stage PCa undergoing AS is not known. It should be noted that, in the present study, we have only investigated free testosterone as a predictor of disease reclassification without any claims regarding causality, which, if present, could theoretically operate in either direction, i.e. PCa may reduce free testosterone concentrations or low free testosterone may contribute to more aggressive PCa. To address this question, it would be necessary to design a study correlating values with low tissue testosterone levels and modulation of androgen-dependent genes that may be implicated in PCa progression.
Ignacio F. San Francisco as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Departamento de Urología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile