de la Fouchardiere C, et al. - Clinical and molecular factors of poor prognosis in poorly differentiated thyroid carcinomas (PDTC) were determined. PDTC formed a heterogeneous group of patients with usual late-stage diagnosis, low radioactive iodine avidity and frequent metastatic spread. Those at high risk of radio-iodine refractoriness could be detected with the help of TERT promoter mutations.

• This study included a total of 104 consecutive patients treated for a PDTC between 01/01/2000 and 31/12/2010.
• For all cases, a pathological review was performed (blinded to clinical data and outcome).

• Data showed that all patients underwent thyroidectomy and adjuvant radioactive-iodine was administered in 95.2% of them.
• Researchers found that in 68.3% of cases, tumours were pT3 or pT4, while metastatic in 38.5% of patients.
• Findings demonstrated that 40% of patients had extrathyroidal extension (ETE).
• Merely 37% of patients were considered in remission at the end of the initial treatment.
• During follow-up, radio-iodine refractoriness was observed in 52 patients (50%).
• They noted that 5-year overall survival was 72.8% and the 5-year recurrence-free survival (RFS) was 45.3%.
• Remission after initial treatment was an independent factor of RFS (HR = 0.22; [0.10–0.49]).
• In multivariate analysis, the only significant parameter that influenced the overall survival was ETE.
• In 38.1% of analysed patients, the presence of TERT promoter mutations at positions -124 (C228T) and -146 (C250T) was noted, which was significantly associated with radioiodine resistance but not with overall survival.
• In addition, data revealed that half of TERT promoter mutant tumours harboured also RAS or BRAF mutations.