A Cochrane review included 16 studies with a total of 1 410 subjects. Two studies of pre-surgical medical therapy (goserelin) showed no evidence of benefit compared to surgery alone. Post-surgical hormonal suppression of endometriosis (either with nafarelin, goserelin, leuprolide, triptorelin, medroxyprogesterone acetate, oral contraceptives, danazol, or traditional Chinese medicine, gestrinone) compared to surgery alone showed no benefit for the outcomes of pain, disease recurrence, or pregnancy rates (RR 0.84, 95% CI 0.59 to 1.18). There were no trials identified in the search that compared hormonal suppression of endometriosis before and after surgery with surgery alone. There is no significant difference between pre-surgery hormonal suppression and post-surgery hormonal suppression for the outcome of pain in the one trial identified (RR 1.01, 95% CI 0.49 to 2.07). Another single trial comparing post-surgical medical therapy with both pre and post-surgery found no difference in the outcomes of American Fertility Society (AFS) scores and pregnancy rate.
Another systematic review included 7 studies (4 RCTs, 1 prospective self-controlled study, 1 cohort study, and 1 retrospective study) with a total of 1 158 subjects evaluating post-operative combined oral contraceptive pill (OCP) treatment on prevention of endometriosis recurrence. A low-dose monophasic oral contraceptive therapy was used in all the studies. Short-term therapy did not reduce recurrence (2 studies). A reduction in anatomical relapse rate was observed when OCP was administered for more than 1 year after conservative surgery; one cohort study (n=277) observed that at 36 months’ follow-up, crude recurrence rate was 9% in the group of patients treated by post-operative OCP for the entire follow-up period and 56% in the untreated group (P < 0.001). Another study (RCT, n=217) observed at 24 months follow-up an endometrioma crude recurrence rate of 29% in untreated patients versus 14.7 and 8.2% in women treated with OCP in cyclic and continuous administration, respectively; the difference was significant between untreated versus women treated with OCP (P < 0.005). Long-term post-operative use of OCP was associated with a reduction in frequency and intensity of dysmenorrhoea recurrence. One RCT (n=271) observed a significant reduction in frequency and severity of recurrent dysmenorrhoea in patients receiving 24 months' OCP therapy compared with surgery alone. Benefits of oral contraceptives were evident since the first follow-up visit, at 6 months, for the patients in continuous treatment, and after 18 months of follow-up in the women treated in cyclic regimen (P < 0.0005). One self-controlled study (n=50) assessed the efficacy of continuous OCP administration in pain relief in women whom post-operative prophylaxis with cyclic OCP failed to prevent dysmenorrhea recurrence and reported a mean reduction in VAS score of 45.95% after 2 years of continuous OCP therapy (P < 0.001). No association was found between OCP therapy and dyspareunia prevention, although the effect of OCP on chronic pelvic pain was conflicting.
Comment: The quality of evidence is downgraded by limitations in study quality (inadequate or unclear allocation concealment and lack of blinding) and by inconsistency (variability in results across studies).