A large Phase 3 trial combining the PATCH and STAMPEDE-1 networks, published in the New England Journal of Medicine, shows that transdermal estradiol patches are as effective as standard injections for treating locally advanced prostate cancer.
The study found that three-year metastasis-free survival was similar between the two treatments, with 87.1% for the patch group versus 85.9% for standard LHRH injections. Patches also suppressed testosterone faster during the first month, avoiding the “testosterone flare” sometimes seen with injections. Five-year overall survival slightly favored patches (81.1% vs. 79.2%), though the difference was not statistically significant.
Side effects differed between treatments. Estradiol patches caused fewer hot flashes (44% vs. 89%) and better bone health, though breast swelling was more common (85%). Patches can be applied at home, reducing clinic visits, while injections require administration in a medical setting.
These results suggest transdermal estradiol could be a practical alternative for patients who want to avoid injections, reduce fracture risk, or improve quality of life by minimizing hot flashes. Though not yet formally licensed for prostate cancer, the findings support its use as an effective off-label option.