MRI-Based Classification Systems Combined with Serum CA125 for Predicting Symptom Recurrence After Ultrasound-Guided High-Intensity Focused Ultrasound Ablation Surgery for Adenomyosis: A Retrospective Cohort Study

Background: The underlying mechanisms of symptom recurrence or established comprehensive predictive models have not yet elucidated. This study aimed to establish a prediction model for symptom recurrence following focused ultrasound ablation surgery (FUAS) in adenomyosis based on magnetic resonance imaging (MRI)-based classification system incorporating serum cancer antigen (CA) 125 levels. Methods: We conducted a retrospective cohort study of 502 adenomyosis patients, divided into recurrence (n=133) and non-recurrence (n=369) groups. Patients were stratified by MRI lesion extent: ≥ 2/3 uterine wall involvement (n=446) vs < 2/3 (n=56). Symptom recurrence (dysmenorrhea and/or menorrhagia) was the primary outcome. Univariate and multivariate logistic regression identified predictors. Receiver operator characteristic curve analysis determined CA125 cutoffs. Kaplan–Meier curves and Cox regression assessed recurrence-free survival. Results: Patients with ≥ 2/3 involvement had higher CA125 (57.9 vs 32.1 U/mL, P< 0.001). Recurrence group had higher CA125 (71.5 vs 51.14 U/mL, P< 0.001). Multivariate analysis identified CA125 (OR=1.002, 95% CI: 1.001– 1.004), diffuse grayscale changes (OR=0.632, 95% CI: 0.407– 0.981), and combined GnRH-a/LNG-IUS therapy (OR=0.504, 95% CI: 0.323– 0.785) as independent predictors. In the ≥ 2/3 subgroup, CA125 > 35 U/mL predicted shorter recurrence-free survival (37.7 vs 43.9 months, P=0.001). The combined model (CA125 ≥ 35 U/mL + lesion ≥ 2/3) yielded an AUC of 0.580 (95% CI: 0.533– 0.626). Conclusion: A preoperative CA125 level ≥ 35 U/mL combined with MRI-based lesion extent ≥ 2/3 uterine wall involvement may effectively identify adenomyosis patients at high risk of post-FUAS recurrence. Further prospective studies are warranted. Plain Language Summary: High CA125 level combined with MRI-based lesion extent ≥ 2/3 uterine wall involvement could better inform symptom recurrence of adenomyosis after FUAS.