Transdermal Estradiol Patches in Locally Advanced Prostate Cancer

Area of Science:

• Oncology
• Endocrinology
• Clinical Trials

Background:

• Androgen-deprivation therapy (ADT) is crucial for prostate cancer management.
• Luteinizing hormone-releasing hormone (LHRH) agonists are standard ADT, but can cause side effects.
• Transdermal estradiol (tE2) offers an alternative ADT with a potentially improved side effect profile.

Purpose of the Study:

• To compare the efficacy and safety of transdermal estradiol (tE2) versus LHRH agonists for androgen-deprivation therapy in prostate cancer.
• To establish noninferiority of tE2 compared to LHRH agonists regarding metastasis-free survival.
• To evaluate secondary outcomes including testosterone suppression, overall survival, and adverse events.

Main Methods:

• Phase 3, randomized, noninferiority trial involving men with locally advanced prostate cancer.
• Patients were assigned to receive either tE2 patches or LHRH agonists.
• Primary endpoint was 3-year metastasis-free survival; secondary endpoints included testosterone levels, overall survival, and safety.

Main Results:

• Transdermal estradiol (tE2) demonstrated noninferiority to LHRH agonists for 3-year metastasis-free survival (87.1% vs. 85.9%, HR 0.96, upper 95% CI 1.11).
• Both treatments effectively achieved and sustained castrate testosterone levels in 85% of patients during the first year.
• tE2 showed a significantly lower incidence of hot flashes (44% vs. 89%) but a higher incidence of gynecomastia (85% vs. 42%) compared to LHRH agonists.

Conclusions:

• Transdermal estradiol (tE2) is a noninferior alternative to LHRH agonists for androgen-deprivation therapy in locally advanced prostate cancer.
• tE2 offers a favorable side effect profile with fewer hot flashes, though gynecomastia is more common.
• The findings support tE2 as a valuable treatment option for prostate cancer patients requiring ADT.