Rare but Complex: Outcomes and Challenges in Managing Composite Follicular-Anaplastic Thyroid Cancer. Academic Article uri icon

Overview

abstract

  • BACKGROUND: A subset of follicular thyroid cancers (FTC) can dedifferentiate into anaplastic thyroid cancer (ATC), forming composite FTC/ATC tumors. The effect of this dedifferentiation on survival outcomes remains unclear. This study aimed to characterize the clinicopathologic features of composite FTC/ATC tumors and assess their disease-specific survival (DSS). PATIENTS AND METHODS: The Surveillance, Epidemiology, and End Results (SEER) database (2000-2020) was used to identify patients with FTC, composite FTC/ATC, and ATC. Propensity score matching (PSM) was performed on the basis of age, sex, race, and histologic subtype. Clinicopathologic characteristics, DSS, and treatment outcomes were compared. RESULTS: A total of 60 patients with composite FTC/ATC were matched to 180 patients with FTC and 180 patients with ATC. Compared with FTC, composite tumors were associated with larger size (p < 0.001), extra-thyroidal extension (ETE) (p < 0.001), lymph node (p < 0.001) and distant metastases (p = 0.002), more external beam radiation (p < 0.001), and chemotherapy (p < 0.001), but less radioactive iodine (RAI) (p < 0.001). Compared with ATC, composite tumors showed less ETE (p = 0.01), fewer lymph node metastases (p = 0.01), less chemotherapy (p = 0.002), and more RAI (p = 0.002). The median survival of patients with co-FTC/ATC was 7 months (p < 0.001). Advanced age (hazard ratio, HR 1.05; 95% confidence intervals, CI 1.02-1.08) and incomplete thyroidectomy (HR 2.58, 95% CI 1.20-5.56) predicted worse DSS. CONCLUSIONS: Composite FTC/ATC tumors have survival outcomes that fall between those of FTC and ATC. Total thyroidectomy is a key component of treatment, as incomplete thyroidectomy is linked to poorer survival. Further research is needed to explore how the proportion of ATC within composite tumors influences survival outcomes.

publication date

  • March 25, 2025

Identity

Digital Object Identifier (DOI)

  • 10.1245/s10434-025-17208-w

PubMed ID

  • 40131622