Thyroid carcinoma brain metastases: radiosurgery outcomes and genomic characterization across histologic subtypes.

Abstract

Thyroid carcinoma brain metastases (TCBM) are rare and bear a poor prognosis. While stereotactic radiosurgery (SRS) has been used as a minimally invasive treatment option for TCBM, data on clinical outcomes remain limited. Here, we assess local control, overall survival, and adverse effects of SRS for TCBM patients. In addition, we perform an exploratory analysis of genetic variants across histologic subtypes of thyroid cancer with brain involvement. We retrospectively analyzed 17 patients with thyroid carcinoma who underwent SRS for a total of 65 brain metastases. Demographic, clinical, tumor, and treatment characteristics were collected. Next-generation sequencing (NGS) was performed using a targeted sequencing panel. Survival outcomes were assessed using Kaplan-Meier (KM) analysis. Univariate and multivariate Cox proportional hazards models were performed to identify predictors of local tumor progression. The cohort consisted of 10 males (58.8%) and 7 females (41.2%), with a mean age of 62 ± 14.2 years. Papillary thyroid carcinoma was the most common histology (70.6%). Median Karnofsky Performance Status was 80 (IQR, 70-90). All lesions were treated with SRS, with a median target volume of 0.11 cc and a median prescribed dose of 24 Gy. Cumulative local control rates were 87.5% at 6 months and 81.6% at 9, 12, and 24 months. DIF occurred in 4 of 17 patients (24%). KM-estimated DIC was 94% at 6 and 9 months, 86% at 12 months, and 54% at 24 months. Overall survival rates were 88.2% at 6 months, 82.4% at 9 months, 76.5% at 12 months, and 55.6% at 24 months. Median overall survival was 33 months (95% CI, 12.6-53.4). Genetic testing suggested variations in molecular profiles across the primary histologic subtypes. Radiation necrosis occurred in 5 of 65 lesions (7.7%), and seizures were reported in 2 patients (11.8%). SRS provides durable local control with acceptable toxicity in patients with TCBM. Despite the small cohort size, these findings support SRS as an effective and safe treatment modality. Larger, prospective studies are warranted to better define prognostic factors and optimize patient selection.