Clinical Outcomes and Prognostic Factors in Uterine Adenosarcoma: A Multicenter Retrospective Cohort Study.

Background/Objectives: Uterine adenosarcoma is a rare uterine malignancy with limited evidence on prognostic factors and long-term outcomes. We aimed to evaluate clinicopathological characteristics, treatment patterns, oncologic outcomes, and prognostic factors associated with disease-free survival (DFS) and overall survival (OS) in patients with uterine adenosarcoma. Methods: This multicenter retrospective cohort study included 43 patients with histopathologically confirmed uterine adenosarcoma who underwent primary surgery at seven tertiary referral centers in Türkiye between 2016 and 2026. Clinicopathological features, treatment modalities, recurrence patterns, and survival outcomes were assessed. Survival was analyzed using Kaplan-Meier and log-rank methods, and multivariable Cox proportional hazards regression was performed to identify independent prognostic factors. Results: The mean age at diagnosis was 59.1 ± 10.8 years, and 83.7% of patients were postmenopausal. Pelvic pain (62.8%) and abnormal uterine bleeding (60.5%) were the most common presenting symptoms. Most patients (79.1%) underwent laparotomy, and 79.1% had stage I disease. Sarcomatous overgrowth (SO) was present in 44.1% and lymphovascular space invasion (LVSI) in 18.6%. During a median follow-up of 72 months, 34.9% experienced recurrence, most commonly in the pelvis. The five-year DFS and OS rates were 59.9% and 80.4%, respectively. SO was independently associated with DFS (HR 4.41, 95% CI 1.21-16.08; p = 0.025) and OS (HR 10.23, 95% CI 1.16-89.80; p = 0.036), while LVSI was independently associated with OS (HR 11.17, 95% CI 1.34-93.14; p = 0.026). Conclusions: Uterine adenosarcoma showed favorable long-term survival but substantial recurrence risk. SO and LVSI may have potential prognostic relevance and could contribute to postoperative risk assessment and individualized follow-up.