Endometriosis recurrence following post-operative hormonal suppression: a systematic review and meta-analysis

BACKGROUND Although surgery for endometriosis can improve pain and fertility, the risk of disease recurrence is high. There is little consensus regarding the benefit of medical therapy in preventing recurrence of endometriosis following surgery. OBJECTIVE AND RATIONALE We performed a review of prospective observational studies and randomised controlled trials (RCTs) to evaluate the risk of endometriosis recurrence in patients undergoing post-operative hormonal suppression, compared to placebo/expectant management. SEARCH METHODS The following databases were searched from inception to March 2020 for RCTs and prospective observational cohort studies: MEDLINE, Embase, Cochrane CENTRAL and Web of Science. We included English language full-text articles of pre-menopausal women undergoing conservative surgery (conserving at least one ovary) and initiating hormonal suppression within 6 weeks post-operatively with either combined hormonal contraceptives (CHC), progestins, androgens, levonorgesterel-releasing intra-uterine system (LNG-IUS) or GnRH agonist or antagonist. We excluded from the final analysis studies with <12 months of follow-up, interventions of diagnostic laparoscopy, experimental/non-hormonal treatments or combined hormonal therapy. Risk of bias was assessed using the Cochrane Risk of Bias Tool for RCTs and the Newcastle-Ottawa Scale (NOS) for observational studies. OUTCOMES We included 17 studies (13 RCTs and 4 cohort studies), with 2137 patients (1189 receiving post-operative suppression and 948 controls), which evaluated various agents: CHC (6 studies, n=869), progestin (3 studies, n=183), LNG-IUS (2 studies, n=94) and GnRH agonist (9 studies, n=1237). The primary outcome was post-operative endometriosis recurrence, determined by imaging or recurrence of symptoms, at least 12 months post-operatively. The secondary outcome was change in endometriosis-related pain. Mean follow up of included studies ranged from 12 to 36 months, and outcomes were assessed at a median of 18 months. There was a significantly decreased risk of endometriosis recurrence in patients receiving post-operative hormonal suppression compared to expectant management/placebo (relative risk (RR) 0.41, 95% CI: 0.26 to 0.65), 14 studies, 1766 patients, I-2 = 68%, random effects model). Subgroup analysis on patients treated with CHC and LNG-IUS as well as sensitivity analyses limited to RCTs and high-quality studies showed a consistent decreased risk of endometriosis recurrence. Additionally, the patients receiving post-operative hormonal suppression had significantly lower pain scores compared to controls (SMD -0.49, 95% CI: -0.91 to -0.07, 7 studies, 652 patients, I-2 = 68%). WIDER IMPLICATIONS Hormonal suppression should be considered for patients not seeking pregnancy immediately after endometriosis surgery in order to reduce disease recurrence and pain. Various hormonal agents have been shown to be effective, and the exact treatment choice should be individualised according to each woman's needs.