The Afirma RNA-Sequencing Medullary Thyroid Carcinoma (MTC) Classifier was able to correctly identify MTC samples from other benign and malignant thyroid samples collected through fine needle aspiration biopsy (FNAB), according to a study published in Thyroid.

In the study, a support vector machine classifier was able to identify MTC FNAB samples with 100% sensitivity, correctly finding all 21 MTC samples. The classifier was also able to achieve 100% specificity by correctly assigning the other 190 thyroid samples tested as negative for MTC.

“This test facilitates the pre-operative diagnosis of MTC to enable appropriate initial treatment of MTC patients with Bethesda categories III-VI FNA cytology,” the authors concluded.

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The authors highlighted the need for correct identification of MTC prior to surgery, as patients who are initially misdiagnosed are at risk of receiving insufficient presurgical care. Cytopathological evaluation of FNAB samples can result in missed MTC diagnoses in half of patients, according to the authors.

Read more about MTC testing.

Feature selection for the classifier was performed on 483 thyroid specimens, including 21 MTC samples, plus an additional 97 tissue samples. The selection of features finally chosen included 108 genes.

The classifier was then trained using the 483 thyroid specimens before being locked and validated on a nonoverlapping set of 211 preoperative FNAB samples which included 21 MTCs. All biopsy samples were surgically confirmed as either positive or negative for MTC.

The training sample included 5 Bethesda category III, 6 Bethesda category IV, 6 Bethesda category V, and 4 Bethesda category VI samples. The samples used in validation included 8 Bethesda category III, 6 category IV, and 7 category V.

“We report the development and blinded, independent clinical validation of the Afirma RNA-Sequencing MTC Classifier. All positive samples had surgical pathology confirmation of MTC, while all negative samples were negative for MTC postoperatively,” the authors said.


Randolph GW, Sosa JA, Hao Y, et al. Preoperative identification of medullary thyroid carcinoma (MTC): clinical validation of the Afirma MTC RNA-Sequencing classifier. Thyroid. Published online July 6, 2022. doi:10.1089/thy.2022.0189