Validation of two predictive models for survival in anaplastic thyroid cancer (ATC)

The prognosis of patients with anaplastic thyroid cancer (ATC) remains dismal. A small portion of patients experience longterm survival and need to be identified before treatment allocation. Survival scores may guide clinicians making more informed decisions about treatment options and improve the understanding of patients' prognosis. The aim of this study was to validate two prognostic scores using an independent dataset to analyze which prognostic index is superior in discriminating survival.

Thirty-four patients with histologically confirmed ATC diagnosed between January 2009 and December 2019 were consecutively treated at our department and evaluated. Next generation sequencing was performed in 7 (21%) patients, but no druggable mutation was found. 50% of all patients received surgery and 56% were treated with chemoradiotherapy. The median radiation dose in equivalent dose in 2 Gy fractions (EQD2) was 50 Gy (SD:21 Gy). The study compared the discrimination of the Sugitani Prognostic Index (SPI) and the Marchand-Crety Prognostic Score (MCPS) using concordance statistics, area under the receiver-operating characteristics curve (AUC), net reclassification index, and integrated discrimination improvement for 6-month survival.

The median survival of the entire cohort was 5 months (range: 1-133). The AUC for 6-month survival was 0.85 (95% confidence interval [CI]:0.72-0.97) for SPI and 0.69 (95% CI: 0.56-0.83) for MCPS (p < 0.0001). Using the net reclassification index (NRI), 73% of patients were correctly reclassified using SPI instead of MCPS for 6-month survival (p = 0.0237).

The SPI was more accurate than the MCPS to determine patients' life expectancies and should be recommended for clinical guidance and treatment allocation. In the last decade, comprehensive genetic profiling of actionable mutations in ATC has become vital to guide targeted therapy.