Afirma genomic sequencing classifier performance in young patients with cytologically indeterminate thyroid nodules

The Afirma Genomic Sequencing Classifier (GSC) is validated in patients ≥ 21 years with a 96% negative predictive value for malignancy when GSC-(B)enign. Afirma GSC has not been formally studied in patients <21 years of age with indeterminate thyroid nodules (ITNs).

To evaluate Afirma GSC in young patients with ITNs.

Retrospective analysis of Afirma GSC testing.

ITNs referred for molecular testing in a real-world setting.

Forty-nine ITNs from 49 patients < 21 years of age who had histopathology or 2 years' clinical follow-up data ascertained.

None.

Afirma GSC test performance.

In 49 ITNs from patients aged 9 to 20 years (median 18.5 [interquartile range, 17.3-19.8]), 30 were GSC-B and 19 GSC-(S)uspicious, among which 14 (73.7%) were malignant (ie, true positive) and 5 (26.3%) were benign (ie, false positive). All 30 Afirma GSC-B cases were either histologically (n = 9) or clinically benign (n = 21) (ie, true negative). All 14 malignancies were GSC-S (sensitivity 100% [95% CI, 77-100]); 30/35 clinically or histologically benign cases were GSC-B (specificity 86% [95% CI, 70-95]). Negative predictive value for an Afirma GSC-B result was 100% [95% CI, 88-100]. Genomic alterations were not detected in the 30 GSC-B samples. Among the 14 malignant samples, there were 9 papillary thyroid carcinomas, 1 oncocytic carcinoma, 1 noninvasive follicular thyroid neoplasm with papillary-like nuclear features, and 3 follicular thyroid carcinomas.

In young patients with ITNs, the Afirma GSC demonstrated an excellent negative predictive value when defining a thyroid nodule result by histology or clinical follow-up.