[Comparative analysis of the efficacy of dienogest and LNG-IUS in the treatment of intrinsic and extrinsic subtypes of adenomyosis].

Objective: To compare the efficacy of dienogest (DNG) and levonorgestrel-releasing intrauterine system (LNG-IUS) in the treatment of intrinsic and extrinsic subtypes of adenomyosis. Methods: Totally 232 patients were enrolled in the study who were diagnosed as adenomyosis by ultrasound or pelvic magnetic resonance imaging (MRI), and were classified into intrinsic and extrinsic subtypes according to different locations of lesions in MRI, treated with DNG (DNG group) or LNG-IUS (LNG-IUS group) in Peking University Third Hospital from July 2019 to December 2023. Clinical data of patients were retrospectively collected to analyze the clinical and imaging characteristics of different MRI subtypes of adenomyosis and whether there were differences in the therapeutic effects of DNG and LNG-IUS. Results: (1) Among the 232 patients enrolled, 129 were intrinsic subtype and 103 were extrinsic subtype. Among the 129 patients treated with DNG, the numbers of intrinsic and extrinsic subtype were 69 and 60, respectively. And among the 103 patients treated with LNG-IUS, the numbers of intrinsic and extrinsic subtype were 60 and 43, respectively. The mean age in DNG group [(37.5±5.6) years] was lower than that in LNG-IUS group [(40.3±4.3) years, P<0.001]. There were no significant differences in other clinical features (all P>0.05). (2) The visual analog scale (VAS) scores of dysmenorrhea and cancer antigen 125 (CA₁₂₅) levels in DNG group and LNG-IUS group were significantly decreased after treatment (all P<0.001), and hemoglobin levels were increased (both P<0.01). Compared between the two groups, the VAS score after treatment was lower in DNG group (P<0.001), and the hemoglobin level was increased more significantly in DNG group (P=0.016). The complete remission rates of dysmenorrhea in DNG group and LNG-IUS group were 73.0% (89/122) and 29.5% (28/95), respectively (P=0.039). The incidence of irregular bleeding in DNG group was higher than LNG-IUS group, but there was no statistical significance [62.8% (81/129) vs 52.4% (54/103), P=0.112]. (3) Among patients with intrinsic adenomyosis, the incidence of menorrhagia was significantly higher than in those with extrinsic adenomyosis (P<0.001), while the incidence and severity of dysmenorrhea were lower compared to extrinsic adenomyosis (P=0.004, P=0.007, respectively). After treatment with DNG and LNG-IUS, there were no statistically significant differences in VAS scores between patients with intrinsic and extrinsic adenomyosis (all P>0.05). The incidence of irregular bleeding after DNG treatment was 78.3% (54/69) in intrinsic adenomyosis, which was higher than the 45.0% (27/60) observed in extrinsic adenomyosis (P<0.01). Similarly, the incidence of irregular bleeding after LNG-IUS treatment was 63.3% (38/60) in intrinsic adenomyosis, higher than the 37.2% (16/43) in extrinsic adenomyosis (P=0.009). (4) DNG treatment (OR=19.163, 95%CI: 7.564-48.544; P<0.01) and duration of treatment (OR=1.043, 95%CI: 1.012-1.075; P=0.007) were independent positive factors for complete remission of dysmenorrhea, while VAS score before treatment (OR=0.654, 95%CI: 0.454-0.942; P=0.023) was negative factor. Intrinsic subtype was an independent risk factor for irregular bleeding (OR=0.436, 95%CI: 0.235-0.811; P=0.009). Conclusions: DNG demonstrates greater advantages over LNG-IUS in terms of complete relief of dysmenorrhea and the degree of symptom alleviation. The incidence of irregular vaginal bleeding in patients with intrinsic adenomyosis is higher than in those with extrinsic adenomyosis. For patients with extrinsic adenomyosis, particularly those with prominent dysmenorrhea symptoms, DNG treatment offers greater benefits. However, for patients with intrinsic adenomyosis and those with significant menstrual disorders, a more cautious approach is required when selecting progestin therapy, along with enhanced monitoring and management.