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Updated: Mar 19, 2026
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
Efficacy of Ethinylestradiol Re-challenge for Metastatic Castration-resistant Prostate Cancer
Takehisa Onishi1, Takuji Shibahara2, Satoru Masui2
1Department of Urology, Ise Red Cross hospital, Ise, Japan takehisa@ise.jrc.or.jp.
Background:
There has recently been renewed interest in the use of estrogens as a treatment strategy for castration-resistant prostate cancer (CRPC). The purpose of this study was to evaluate the feasibility and efficacy of ethinylestradiol re-challenge (re-EE) in the management of CRPC.
Patients And Methods:
Patients with metastatic CRPC who received re-EE after disease progression on prior EE and other therapy were retrospectively reviewed for prostate-specific antigen (PSA) response, PSA progression-free survival (P-PFS) and adverse events.
Results:
Thirty-six re-EE treatments were performed for 20 patients. PSA response to the initial EE treatment was observed in 14 (70%) patients. PSA response to re-EE was 33.3% in 36 re-EE treatments. The median P-PFS for patients treated with initial and re-EE was 7 months and 4 months, respectively. Interestingly, PSA response to re-EE was observed even in non-responders to initial EE, and those treated with multiple re-EE. No patients developed cardiovascular or thromboembolic events.
Conclusion:
Re-EE may be safely repeated several times and can lead to a prolonged disease control in selected patients. Re-challenge with EE appears to be a reasonable option worth considering for patients with metastatic CRPC.
