When patients with prostate cancer require androgen deprivation therapy, delivering part of the treatment via a transdermal estradiol patch may be as effective as traditional approaches while reducing adverse effects, according to a phase 2 trial.

Prostate cancer cells typically depend on androgens such as testosterone for growth. Androgen deprivation therapy (ADT) includes androgen receptor pathway inhibitors and luteinizing hormone-releasing hormone (LHRH) agonists or antagonists, which suppress testosterone production via injection or implantation.

Adverse effects of ADT include vasomotor symptoms, fatigue, cognitive impairment, and bone density loss.

In a trial presented at the 2025 ASCO Genitourinary Cancers Symposium, 79 patients received androgen receptor pathway inhibitors plus either LHRH drugs or a transdermal estradiol patch.

Within six months, PSA responses were comparable between groups (61% in both). Estradiol patches were associated with lower rates of vasomotor symptoms (5% vs. 24%) and hypertension (5% vs. 17%) but increased rates of gynecomastia.

Previous trials suggest estradiol patches are non-inferior to LHRH agonists in androgen suppression and metastasis-free survival while offering metabolic and bone density benefits.

"Repurposing of an older, cheap drug is an important way to improve outcomes, separate from developing new drugs,” said study author Nick James, MD, of the Institute of Cancer Research, The Royal Marsden NHS Foundation Trust, London.