Estetrol Prevents Hot Flushes and Improves Quality of Life in Patients with Advanced Prostate Cancer Treated with Androgen Deprivation Therapy: The PCombi Study

Background: Androgen deprivation therapy (ADT) for prostate cancer (PCa) is accompanied by side effects affecting health-related quality of life (HRQL). Objective: To assess the effects of the fetal estrogen estetrol (E4) on symptoms related to estrogen and androgen deficiency, and on HRQL measured using the validated Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire. Design, setting, and participants: This was a phase 2, double-blind, randomized, placebo-controlled study in patients with advanced PCa. Intervention: Patients receiving ADT were randomly assigned at a 2:1 ratio to daily treatment with a high dose of E4 (HDE4; n = 41) or placebo (n = 21) for 24 wk. Outcome measurements and statistical analysis: The primary outcome was the effect of HDE4 cotreatment on hot flushes (HFs). Secondary outcomes were the Q-Man questionnaire for evaluation of the effect on estrogen and androgen deficiency symptoms, and the FACT-P questionnaire for evaluating HRQL. Results and limitations: At 24 wk, the number of patients experiencing HFs was significantly lower in the HDE4 group than in the placebo group (14.3% vs 60.0%; p < 0.001). HDE4 treatment was associated with lower incidence of night sweats, arthralgia, and fatigue, but more nipple tenderness and gynecomastia. At 24 wk, the mean HRQL score favored HDE4 over placebo for the FACT-P total score (122.2 ± 12.3 vs 118.7 ± 19.7) and for several other FACT subscales. Conclusions: Daily HDE4 coadministration almost completely prevented HFs in patients with advanced PCa treated with ADT. HDE4 also had positive effects on HRQL and counteracted other estrogen deficiency symptoms caused by ADT. These data support the dual efficacy concept of ADT and HDE4 to improve HRQL and increase the antitumor effect of ADT. Patient summary: For patients on androgen deprivation therapy for advanced prostate cancer, cotreatment with a high dose of estetrol almost completely prevents the occurrence of hot flushes and improves quality of life and well-being, but nipple sensitivity and an increase in breast size may occur.