Has Afirma gene expression classifier testing refined the indeterminate thyroid category in cytology?

Abstract

BACKGROUND: Thyroid fine-needle aspiration (FNA) plays a pivotal role in the evaluation of thyroid nodules. Up to 30% of cases are diagnosed as indeterminate by FNA, including atypia of undetermined significance, follicular lesion of undetermined significance, suspicious for a follicular neoplasm, and follicular neoplasm, with approximately two-thirds having a benign outcome. The gene expression classifier (GEC) test is a molecular test for cases with indeterminate cytology. The purpose of the current study was to examine the refining role of the GEC test within a single institution. METHODS: Retrospective analysis of all thyroid FNAs during a 20-month period after implementation of GEC was performed. Cases of indeterminate cytology with concomitant GEC testing were selected and divided further in 4 subgroups. Correlation with surgical follow-up, when available, was performed. The results were compared with previously published data from the study institution before the implementation of GEC testing. RESULTS: Among the 217 cases, there were 189 with indeterminate cytology, 42% of which were benign and 50% of which were suspicious by GEC. The excisional rate of atypia of undetermined significance-follicular lesion of undetermined significance in the pre-GEC category was 63%, which decreased to 35% in the post-GEC category, whereas the malignancy rate in the excised thyroids increased from 35% in the pre-GEC category to 47% in the post-GEC category. Similar findings also were obtained for suspicious for a follicular neoplasm-follicular neoplasm lesions. CONCLUSIONS: The strength of the GEC test appears to lie in its ability to reclassify 42% of indeterminate cytology cases as benign, thereby decreasing the number of unnecessary surgical procedures. Cancer (Cancer Cytopathol) 2016;124:100-9.

Impact of the Afirma Gene Expression Classifier Result on the Surgical Management of Thyroid Nodules with Category III/IV Cytology and Its Correlation with Surgical Outcome

“…Although Afirma's overall sensitivity and NPV in thyroid nodules with category III/IV cytology were both 100% due to the absence of false negative cases, its specificity and PPV were only 15 and 38%, respectively. These analytical performance characteristics are consistent with the observations of another study [19]. However, the fact that only 8 cases with a benign Afirma result were surgically confirmed limited the accuracy of the sensitivity, specificity and NPV of the Afirma GEC test obtained in the current study, the results of which should therefore be interpreted with caution.…”

A panel of four genes accurately differentiates benign from malignant thyroid nodules

“…Many studies have shown that genetic background is different between Asians and Western populations. For example, a gene expression classifier (Afirma) showed distinctly different sensitivity and specificity in different populations partly because of different genetic background [13, 20, 22–25]. What is more, Xing M et al reported BRAF mutation occurred in about 45 % of PTC patients in the USA [26] while the rate reported in Asian was much higher, 63.7 % in the study from Jin L et al [27] and 58 % in the study from Lee JH [28].…”

When Is Thyroidectomy the Right Choice? Comparison between Fine-Needle Aspiration and Final Histology in a Single Institution Experience

“…Our prevalence of malignancy was higher than outlined by the 2014 National SIAPEC-IAP guidelines [9] , The Bethesda System [7] (where the TIR-3A category is considered analogous to AUS/FLUS, and the TIR-3B category is considered analogous to FN/SFN), and the British Thyroid Association Royal College of Physicians guidelines [11] (in which the TIR-3A category corresponds to THY-3a, and TIR-3B category to THY-3f). This discrepancy is rather frequent in the international literature [25][26][27][28][29] , suggesting that TIR-3A and TIR-3B should be both considered as intermediate/high-risk categories. For this reason, a surgical approach should be considered for both categories rather than only for TIR-3B, as is recommended by the most important international guidelines [7,9,11] .…”