Association of radiotherapy with survival outcomes in primary uterine leiomyosarcoma: a SEER database study

To evaluate the association between radiotherapy (RT) and long-term survival in patients with primary uterine leiomyosarcoma (uLMS) using a large, population-based cohort. Data of 2384 adults (2010–2021) with histologically confirmed primary uLMS were extracted from the SEER-17 database. Patients were classified into “no-RT” ( n = 2046) and “RT” ( n = 338) groups. After propensity-score matching (PSM), 1570 no-RT and 335 RT patients remained. Cancer-specific survival (CSS) and overall survival (OS) were compared with Kaplan-Meier and multivariable Cox models. Subgroup analyses were performed for all pre-set subgroups. Before PSM, CSS and OS did not differ between groups (CSS HR = 1.10, p = 0.199; OS HR = 1.08, p = 0.336). After PSM, survival remained equivalent (CSS HR = 1.00, 95% CI 0.86–1.17, p = 0.998; OS HR = 0.97, 95% CI 0.84–1.13, p = 0.725). Radiotherapy was not independently associated with survival on multivariate analysis (CSS, p = 0.238; OS, p = 0.131). A modest OS benefit was observed only in the chemotherapy-received subgroup (HR = 0.83, p = 0.046); conversely, CSS was inferior with RT in pulmonary-metastasis and no-chemotherapy subgroups. In this SEER-based cohort, RT was not associated with improved CSS or OS in the overall population of patients with primary uLMS. Any potential benefit appears restricted to highly selected subgroups and requires prospective validation. Surgical resection remains the cornerstone of curative therapy.