The efficacy and tolerability of short-term low-dose estrogen-only add-back therapy during post-operative GnRH agonist treatment for endometriosis.

OBJECTIVE: To evaluate the efficacy and tolerability of a low-dose estrogen-only regimen as a short-term add-back therapy during post-operative GnRH agonist (GnRHa) treatment of patients with endometriosis.

STUDY DESIGN: Retrospective cohort study. One hundred seventeen women of reproductive age who were treated with post-operative GnRHa after conservative laparoscopic surgery for endometrioma were eligible for this study. The patients were divided into two groups: group A (n = 56) received tibolone (2.5mg) between 2002 and 2004 and group B (n = 61) received estradiol valerate (1mg) between 2005 and 2007 as an add-back therapy for five months, beginning at the time of the second injection of a GnRHa. The incidence of hypoestrogenic symptoms and the degree of pelvic pain according to a verbal rating scale (VRS) scoring system, the incidence and patterns of uterine bleeding during add-back therapy, the endometrial thickness by ultrasonography two months after the last GnRHa treatment, and the serum CA-125 level were evaluated.

RESULTS: The incidence of uterine bleeding, hypoestrogenic symptoms such as hot flashes and sweating, and pelvic pain did not differ significantly between the two treatment groups. However, the endometrium was thicker in group A than group B (p = 0.022). In group B, the frequency of uterine bleeding was lower from the second month after starting add-back therapy than in group A, but without statistical significance (at the sixth month, p = 0.086).

CONCLUSION: The low-dose estrogen-only regimen was efficacious and tolerable as a short-term add-back therapy during post-operative GnRHa treatment after surgery for endometriosis.