Survival Outcomes of Advanced Thyroid Cancer Enriched in Brain Metastases Following Treatment With Small Molecule Inhibitors

Small molecule inhibitors (SMIs) are targeted therapies increasingly used in advanced thyroid carcinomas. This study aimed to evaluate the survival outcomes of thyroid cancer on SMI treatment, including in patients with brain metastases.This retrospective study included patients with thyroid carcinomas who received at least one SMI between 2008 and 2022 at a tertiary level, academic institution. SMI included lenvatinib, sorafenib, dabrafenib-trametinib, selpercatinib, and cabozantinib. Patients were grouped by the presence of brain metastasis. Kaplan-Meier and log-rank tests modeled the overall survival (OS), defined from detection of first metastasis.In total, 116 patients (49.1% female, median age 61.1 years [IQR, 51.1-71.0]) were included. Thyroid cancer subtypes were: 57 (49.6%) papillary, 23 (19.8%) anaplastic, 23 (19.8%) medullary, and 13 (11.2%) follicular. There were 18 (15.5%) patients with brain metastases, and 98 (84.5%) with visceral metastases. Age, sex, thyroid subtype, SMI, and time to recurrence were not different between cohorts. OS was shorter in the brain metastasis cohort (31.7 vs 42.2 months, P =.44) and was not different after excluding anaplastic thyroid cancer (29.1 vs 62.3 months, P =.21). In the case of papillary thyroid cancer, patients with brain metastases trended toward worse OS (22.0 vs 59.9 months, P =.13). Nonanaplastic histology, total thyroidectomy (OR, 40.0; P <.001), number of unique therapies (OR, 10.9; P =.047), and mutation-directed therapy (OR, 24.7; P =.003) were associated with improved OS.This single-institutional analysis reports survival outcomes of 116 patients with advanced thyroid cancer on targeted therapies, including 18 patients with brain metastases. Mutation-directed therapy for BRAFV600E mutations, RET mutations, RET fusions, and NTRK fusions had superior survival.