RDTA-07 STEREOTACTIC RADIOSURGERY FOR BRAIN METASTASES ORIGINATING FROM THYMIC TUMORS

Abstract Brain metastases (BM) originating from tumors arising from the thymus are rare, with limited data available regarding the incidence and prevalence. Stereotactic radiosurgery (SRS) is an established treatment modality for BM. This retrospective study reviewed all patients diagnosed with TT and BM who underwent SRS, and we discovered 4 patients after screening. The tumor control was defined as per the RECIST criteria, and survival outcomes were calculated using Kaplan-Meier analysis. The median age at treatment was 67 years (range: 43–70). Half of the patients were diagnosed with malignant thymoma, while the remaining patients had a neuroendocrine tumor and thymic carcinoma, respectively. One patient had a prior history of WBRT, and two patients had a history of previous brain surgery. The median KPS was 55 (range: 50–90), while the median ECOG status was 2 (range: 1–3). The mean tumor diameter was 22.5 mm (range: 11–35), and the median tumor volume was 2.87 cm³ (range: 0.78–14.4). The median prescribed SRS dose was 20 Gy (range: 18–24), with a maximum dose of 26.78 Gy (range: 23.08–33.33). All patients received treatment in a single fraction, with a median isodose line of 75% (range: 70–80). The median follow-up duration was 5 months (range: 2.13–7.03). 50% of patients showed local recurrence. KM analysis showed a 3-month LTC rate of 75%. The median OS was 5 months (95% CI: 2.45–7.54), with 3-month and 6-month OS rates of 75% and 25%, respectively. All patients eventually succumbed to systemic disease progression. These findings suggest that SRS may serve as a viable treatment option for BM secondary to thymic tumors. However, larger studies are needed to further evaluate the efficacy of SRS and to identify factors influencing outcomes in this patient population.