Comparison of the gonadotropin-releasing hormone agonist goserelin acetate alone versus goserelin combined with estrogen-progestogen add-back therapy in the treatment of endometriosis

OBJECTIVE: To investigate whether the addition of low-dose estrogen-P combination hormone replacement therapy (HRT) to GnRH agonist (GnRH-a) treatment for endometriosis reduces the pharmacologic side effects of such treatment without reducing efficacy and to determine the endocrinologic changes during treatment. DESIGN: Prospective, randomized, double-blind, placebo-controlled, comparative study of two drug regimens: 3.6 mg goserelin acetate in a 28-day SC depot formulation once monthly for 6 months plus either a combination of 2 mg 17 beta-E2 and 1 mg norethisterone acetate (NET) 1 mg or matching placebo tablets once daily for 6 months. SETTING: Multicenter study in three tertiary referral centers at university teaching hospitals and two central hospitals. PATIENTS: Women with laparoscopically confirmed symptomatic endometriosis were included in the study. RESULTS: Of the total of 109 patients screened, 93 were recruited and 88 patients were randomized to either the HRT or the placebo group. Four women were withdrawn because of various medical reasons, and 76 patients were followed-up for a total of 12 months. In terms of efficacy, there was no difference between the two drug regimens for objective or subjective response. There were significantly less postmenopausal symptoms in the patients treated with goserelin plus HRT compared with those treated with goserelin plus placebo. CONCLUSION: Goserelin diminished significantly the symptoms and laparoscopic scores of endometriosis. The addition of HRT did not reduce the efficacy of goserelin but diminished the postmenopausal symptoms during treatment.