Anaplastic Transformation of Differentiated Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) is a rare but highly aggressive form of thyroid cancer. Increasingly, patients with ATC present with concurrent foci of well-differentiated thyroid carcinoma (WDTC); however, the significance of these pathologic findings remains unclear. The objective of this study is to determine whether the presence of WDTC within anaplastic tumors is a prognosticator of survival.

A retrospective cohort study of all cases of biopsy-proven ATC managed at a tertiary care academic medical center from 2002 to 2020 was performed. Mean age at diagnosis, median survival time, and locations of distant metastases were assessed. The impact of clinical markers such as presence of differentiation, demographic variables, and oncologic information on overall survival was also determined via univariate and multivariate analysis.

Forty-five patients were included in this study. The mean age at diagnosis was 69.1 years. Median survival time was 6.1 months after diagnosis. The most common location of distant metastases was the lung (40%). The presence of limited areas of WDTC in patients with predominantly anaplastic thyroid tumors was not significantly associated with improved outcomes (p = 0.509). Smaller tumor size and use of chemotherapy in ATC patients were significantly associated with prolonged survival (p = 0.026 and 0.010, respectively).

Clinical outcomes for ATC remain poor. The presence of foci of differentiation within anaplastic thyroid tumors does not appear to improve overall survival-the anaplastic component evidently drives outcomes. Further studies into novel therapies are needed to improve survival in ATC.

4 Laryngoscope, 133:437-442, 2023.