Efficacy of Post-Operative Medication to Prevent Recurrence of Endometrioma: Cyclic Oral Contraceptive (OC) After Gonadotropin-Releasing Hormone (GnRH) Agonist Versus Dienogest

Background: There are several medical treatment options for endometrioma. Progestin, especially dienogest, is an effective drug for preventing recurrence of endometrioma after surgery. Additionally, oral contraceptive (OC) use after conservative surgery has been reported to reduce significantly the risk of endometrioma recurrence. The aim of this study was to compare the long-term effects of gonadotropin-releasing hormone (GnRH) agonist followed by OC to those of dienogest alone to prevent recurrence of endometrioma after laparoscopic surgery. Methods: A retrospective cohort study was performed on patients who underwent conservative laparoscopic surgery for endometrioma between January 2000 and December 2020, in the Endometriosis Clinic, Department of Gynecology, Samsung Medical Center. A total of 624 patients who received medical treatment at least six months after laparoscopic conservative surgery for endometrioma was included. Among them, 372 patients used OC after GnRH agonist therapy, and 252 patients used dienogest. Within the OC group, 148 used a 21/7 regiment and 224 used a 24/4 regimen. A cumulative endometrioma recurrence curve was presented using the Kaplan-Meier method to compare the recurrence of those groups. Results: The cumulative recurrence rate of endometrioma for 60 months was 2.08% (n = 4) in the OC after GnRH agonist group and 0.40% (n = 1) in the dienogest group. There was no statistical difference in cumulative recurrence of endometrioma between the two groups. In subgroup analysis, the cumulative recurrence rate of endometrioma over 60 months was 4.21% (n = 2) in the 21/7 OC group and 1.09% (n = 2) in the 24/4 OC group and showed no significant difference. Conclusion: Long-term use of OC after GnRH agonist as well as that of dienogest treatment are effective postoperative medical therapies for preventing endometrioma recurrence. Thus, the choice of regimen can be individualized or used interchangeably depending on patient condition, need for contraception, and compliance with drug therapy.