Low-Dose Oral Ethinylestradiol With Concomitant Low-Dose Acetylsalicylic Acid for Advanced Castrate-Resistant Prostate Cancer.

The aim of the present study was to evaluate the activity and tolerability of low-dose oral ethinylestradiol (EE) and luteinizing hormone-releasing hormone analogue with concomitant low-dose acetylsalicylic acid (ASA) as a thromboprophylactic agent for advanced castrate-resistant prostate cancer (CRPC).

The patients received an EE dose of 150 μg daily (50 μg 3 times daily) and an ASA dose of 100 mg once daily. The primary endpoint was the prostate-specific antigen response.

A total of 32 patients were enrolled. A PSA response was observed in 19 patients (59.3%; 95% confidence interval [CI], 41%-76%). The median progression-free survival was 9.4 months (95% CI, 6.5-14.1 months). The treatment was generally well tolerated and no grade 3-4 toxicity was observed. Only 1 patient interrupted EE because of a cardiac event and 1 patient experienced grade 2 nausea and vomiting. No major bleeding occurred.

Low-dose EE with concomitant low-dose ASA is safe, showing potential activity in patients with advanced CRPC, and should be investigated further.