The Effect of Letrozole Combined with Dydrogesterone for Endometriosis in China: A Meta-Analysis

PURPOSE: To discuss the effects of dydrogesterone combined with letrozole on the effectiveness, sex hormone levels, and serological indicators in patients with endometriosis. This study is registered with PROSPERO (CRD42020213172). METHODS: We searched relevant randomized controlled trials (RCTs) through PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, and VIP Database. The standardized mean differences (SMDs), the mean differences (MDs), or odds ratios (ORs) with their 95% confidence intervals (95% CIs) were computed to be outcome indicators, including total effectiveness, Vascular Endothelial Growth Factor (VEGF) level, Carbohydrate Antigen 125 (CA125) level, Follicle-Stimulating Hormone (FSH) level, Luteinizing Hormone (LH) level, estrogen (E2) level, progesterone (P) level, interleukin-6 (IL-6) level, and tumor necrosis factor-a (TNF-a) level. RESULTS: A total of 19 RCTs involving 1,591 patients were included in this study. Our results showed that letrozole combined with dydrogesterone can significantly reduce the levels of VEGF (SMD -2.23, 95% CI -2.39 to -2.07; p < 0.00001), CA125 (MD -10.53, 95% CI -11.19 to -9.88; p < 0.00001), E2 (SMD -1.64, 95% CI -1.81 to -1.47; p < 0.00001), P (MD -5.11, 95% CI -6.26 to -3.96; p < 0.00001), IL-6 (MD -4.41, 95% CI -5.16 to -3.67; p < 0.00001), and TNF-a (MD -5.67, 95% CI -6.34 to -5.00; p < 0.00001) in patients with endometriosis compared with the control group. In addition, the results indicated that total effectiveness was significantly higher in the experiment group (OR 6.21, 95% CI 4.17 to 9.24; p < 0.00001) compared to the control. However, there was no significant difference between FSH and LH levels in both groups (p > 0.05). CONCLUSION: This combination therapy can effectively decrease the levels of VEGF, CA125, E2, P, IL-6, and TNF-a and increase the total effectiveness when comparing with the control group.