Prognostic of recurrence and survival in poorly differentiated thyroid cancer.

The prognosis of poorly differentiated thyroid carcinomas (PDTC) defined by the Turin criteria is variable. The aim of this study on 51 PDTC patients was to determine clinical, histological and molecular prognostic factors associated with recurrence in patients with localized disease at initial treatment and with overall survival in patients with distant metastases. Of 40 patients for whom next-generation sequencing (NGS) by ThyroSeq v3 was able to be performed on historical samples, we identified high-risk molecular signature (TERT, TP53 mutations) in 24 (60%) cases, intermediate risk signature in 9 (22.5%) cases and low-risk signature in 7 (17.5%) cases. Potentially actionable mutations were identified in 10% of cases. After a median follow-up of 57.5 months, recurrence occurred in 11 (39%) of the 28 patients with localized disease. The American Thyroid Association (ATA) high risk of relapse, high mitotic count, high molecular risk signature and CD163 expression were associated with recurrence (P = 0.009, 0.01, 0.049, 0.03 respectively). After a median follow-up of 49.5 months, thyroid cancer-related death occurred in 53% of the patients with distant metastases. There was no significant prognostic factor associated with death in univariate analysis. However, none of the patients with intermediate ATA risk of recurrence and none of the patients with low-risk molecular signature died from the disease. In addition, high molecular-risk signature was associated with the presence of synchronous or metachronous distant metastasis (P = 0.007) and with poor overall survival (P = 0.01). In conclusion, ATA risk of relapse and high mitotic count was associated with higher rate of recurrence in localized PDTC. High molecular-risk signature was associated with the presence of distant metastasis and poor overall survival. Further studies are needed to determine if molecular testing adds to ATA risk stratification or response to therapy in predicting outcomes.

Impact of expert review of histological diagnosis of papillary and follicular thyroid cancer.

PURPOSE: Histologic and pTNM classification of differentiated thyroid cancer (DTC) is mandatory to assess risk of relapse, risk of death, and radioactive iodine administration. The impact of an expert central review of external pathology reports has not yet been reported. METHODS: Monocentric retrospective study to evaluate the difference between initial and second-opinion histopathologic diagnosis for DTC patients referred for post-operative radioactive iodine administration between January 2014 and December 2016. We evaluated major discordance (change of diagnosis from malignant to benign or in main histological subtype or a description of aggressive pathological subtypes), minor discordance (change in histological subtype or description of an aggressive component, multifocality or extrathyroidal extension), and change in ATA classification. RESULTS: A second-opinion histological diagnosis was available for 199 patients. A major discordance was observed in 42 (21%) cases (changes in malignancy in 4 cases, changes in main histological subtype in 22, changes in aggressive pathology variants of PTC in 16). One hundred and four minor discordances were observed regarding 92 patients. These histopathological changes led to changes in the ATA 2015 risk stratification classification in 61 (31%) of cases. There were no predictive factors of major/minor histologic changes or ATA risk stratification changes. CONCLUSION: Expert central review of pathology has an impact on the 2015 ATA risk stratification classification that can lead to changes in the management of patients with differentiated thyroid cancer.