Key randomized controlled trial outcomes: degarelix trials showed rapid and durable testosterone suppression versus leuprolide with faster PSA decline and, in subgroup analyses, lower risk of PSA progression or death in some patients (Klotz et al; Tombal et al).
In oncology/fertility preservation RCTs, triptorelin (PROMISE-GIM6) reduced chemotherapy-induced early menopause (absolute difference −17%, p<0.001); the SOFT trial found no overall DFS benefit adding ovarian suppression to tamoxifen in the entire cohort but suggested benefit in women who remained premenopausal after chemotherapy.
Single-arm and pivotal trials for pediatric CPP (Fensolvi) achieved the primary LH suppression endpoint in ~87% at 6 months with sex-steroid suppression in most patients.
Systematic reviews and meta-analyses of GnRHa for ovarian protection report mixed results: some meta-analyses show reduced rates of premature ovarian failure or improved resumption of menses, while other RCTs and pooled analyses are inconsistent for ovarian reserve markers and pregnancy rates; significant heterogeneity and variable trial quality were noted.
Guideline positions and reviews (ASCO, UpToDate, Endocrine Society) caution limited or low-quality evidence for some off-label fertility-preservation uses and recommend that ovarian suppression for fertility preservation be considered investigational or used in clinical trials; UpToDate supports selective use (e.g., to induce amenorrhea or to prevent luteal-phase porphyria attacks).
Limitations include heterogeneity of study designs, mixed-quality evidence, small sample sizes, variable endpoints (menstrual resumption vs ovarian reserve vs pregnancy), and inconsistent long-term fertility outcomes—all of which temper broad coverage beyond listed, evidence-supported indications.