Estrogen therapy in patients with prostate cancer: a contemporary systematic review

To evaluate the effectiveness and harms of DES in treating prostate cancer compared to other forms of androgen deprivation therapy (orchiectomy, LHRH agonists, and anti-androgens).

We included clinical trials comparing DES with other forms of ADT (bicalutamide, flutamide, LHRH agonists, or orchiectomy) in PCa treatment. The primary outcomes were overall survival, cancer-specific survival, and progression-free survival, and secondary outcomes were cardiovascular effects. We searched in MEDLINE, EMBASE, Central, and Lilacs from inception to nowadays and saturated information for unpublished data in other sources. We performed a qualitative analysis of all included studies. It was not possible to perform meta-analysis due to low-quality trials and high heterogeneity.

Overall, 1700 references were scanned and 14 prospective randomized trials with a total of 3986 patients were included in the final analysis. Although trials showed DES as similarly effective to another forms of ADT, evidences about cardiovascular toxicity in out of date high doses have discouraged its use. In doses of 1 mg, DES has been used as secondary line PCa treatment with safety.

DES might be similarly effective to other forms of ADT on advanced PCa patients, with potential important roles. Intriguingly, the burden of severe cardiovascular toxicity is mainly related to old-fashioned doses of 5.0 and 3.0 mg. Modern PCa hormonal knowledge warrants stout high-quality prospective randomized trials in the low-dose 1 mg DES scenario.