Defining a new testosterone threshold for medical castration: Results from a prospective cohort series
DOI:
https://doi.org/10.5489/cuaj.471Keywords:
testosterone measurement, androgen deprivation therapy, castration, castrate resistant prostate cancer, prostate cancerAbstract
Background: We seek to determine if testosterone levels below the accepted castration threshold (50 ng/dL) have an impact on time to progression to castrate-resistant prostate cancer (CRPC).
Methods: This is a prospective cohort series of patients undergoing androgen deprivation therapy (ADT) with luteinizing hormone-releasing hormone agonist or antagonist at a tertiary centre from 2006 to 2011. Serum testosterone level was assessed every 3 months. Patients with any testosterone >50 ng/dL were excluded. Patients were stratified into groups based on those achieving mean testosterone levels <20 ng/dL and <32 ng/dL. Progression to CRPC was assessed with the Kaplan-Meier method and compared with the log-rank test.
Results: A total of 32 patients were included in this study. Mean patient follow-up was 25.7 months. Patients with a 9-month serum testosterone <32 ng/dL had a significantly increased time to CRPC compared to patients with testosterone 32 to 50 ng/dL (p = 0.001, median progression-free survival (PFS) 33.1 months [<32 ng/dL] vs. 12.5 months [>32 ng/dL]). Patients with first year mean testosterone <32 ng/dL also had a significantly increased time to CRPC compared to 32 to 50 ng/dL (p = 0.05, median PFS 33.1 months [<32 ng/dL] vs. 12.5 months [32-50 ng/dL]). A testosterone <20 ng/dL compared to 20 to 50 ng/dL did not significantly predict with time to CRPC.
Conclusion: This study supports a lower testosterone threshold to define optimal medical castration (T <32 ng/dL) than the previously accepted standard of 50 ng/dL. Testosterone levels during ADT serve as an early predictor of disease progression and thus should be measured in conjunction with prostate-specific antigen.
Downloads
Downloads
Published
How to Cite
Issue
Section
License
You, the Author(s), assign your copyright in and to the Article to the Canadian Urological Association. This means that you may not, without the prior written permission of the CUA:
- Post the Article on any Web site
- Translate or authorize a translation of the Article
- Copy or otherwise reproduce the Article, in any format, beyond what is permitted under Canadian copyright law, or authorize others to do so
- Copy or otherwise reproduce portions of the Article, including tables and figures, beyond what is permitted under Canadian copyright law, or authorize others to do so.
The CUA encourages use for non-commercial educational purposes and will not unreasonably deny any such permission request.
You retain your moral rights in and to the Article. This means that the CUA may not assert its copyright in such a way that would negatively reflect on your reputation or your right to be associated with the Article.
The CUA also requires you to warrant the following:
- That you are the Author(s) and sole owner(s), that the Article is original and unpublished and that you have not previously assigned copyright or granted a licence to any other third party;
- That all individuals who have made a substantive contribution to the article are acknowledged;
- That the Article does not infringe any proprietary right of any third party and that you have received the permissions necessary to include the work of others in the Article; and
- That the Article does not libel or violate the privacy rights of any third party.