The Largest Known Survival Analysis of Patients with Brain Metastasis from Thyroid Cancer Based on Prognostic Groups

PURPOSE: To analyze the clinical features and prognostic factors associated with the survival of patients with a very rare occurrence of brain metastasis (BM) from differentiated thyroid cancer (DTC). METHODS AND MATERIALS: A total of 37 patients with DTC who were diagnosed with BM between 1995 and 2014 were included. We reviewed the clinical characteristics, treatment modalities, and image findings of BM. Factors associated with survival were evaluated, and the patients were divided into three prognostic groups (Groups A, B, and C) for comparative analysis. RESULTS: The median age at BM was 63 years, and the median time from initial thyroid cancer diagnosis to BM was 3.8 years. The median survival and the 1-year actuarial survival rate after BM were 8.8 months and 47%, respectively. According to univariate and multivariate analyses, four good prognostic factors (GPFs) were identified including age ≤ 60 years, PS ≤ ECOG 2, ≤ 3 BM sites, and without extracranial metastasis prior to BM. Three prognostic groups were designed based on age and number of remaining GPFs: patients ≤ 60 years of age with at least 2 GPFs (Group A) had the most favorable prognosis with a median survival of 32.8 months; patients ≤ 60 years of age with fewer than 2 GPFs and those > 60 years of age with at least 2 GPFs (Group B) had an intermediate prognosis with a median survival of 9.4 months; and patients > 60 years of age with fewer than 2 GPFs (Group C) had the least favorable prognosis with a median survival of 1.5 months. CONCLUSIONS: The survival of patients with BM form DTC differed among the prognostic groups based on the total number of good prognostic factors.