Performance of Afirma genomic sequencing classifier and histopathological outcome in Bethesda category III thyroid...

There is limited data comparing the performance of Afirma Genomic Sequencing Classifier (GSC) in thyroid nodules carrying an initial versus a repeat diagnosis of atypia of undetermined significance (AUS). This study reported an institutional experience in this regard.

This retrospective study included consecutive thyroid nodules that had an initial or a repeat AUS diagnosis and had a subsequent GSC diagnostic result (benign or suspicious) from 2017 to 2021. All nodules were followed by surgical intervention or by clinical and/or ultrasound monitoring. GSC's benign call rate (BCR), rate of histology-proven malignancy associated with a suspicious GSC result, and diagnostic parameters of GSC were calculated and compared between the two cohorts (initial versus repeat AUS). Statistical significance was defined with a p-value of <.05 for all analysis.

A total of 202 cases fulfilled inclusion criteria, including 67 and 135 thyroid nodules with an initial and a repeat AUS diagnosis, respectively. BCR was 67% and 66% in initial and repeat AUS cohorts, respectively. Rate of histology-proven malignancy associated with a suspicious GSC result were 22% and 24% in initial and repeat AUS cohorts, respectively. Compared with the repeat AUS cohort, the initial AUS cohort showed slightly lower sensitivity (83% vs. 100%), specificity (70% vs. 73%), PPV (23% vs. 24%), NPV (98% vs. 100%), and diagnostic accuracy (72% vs. 75%). Nevertheless, these differences did not reach statistical significance.

GSC demonstrated comparable performance in thyroid nodules with a repeat AUS diagnosis versus nodules with an initial AUS diagnosis.