EP87 – Community Endocrine Surgical Experience With False Negative Afirma GEC Results

      Harrell, R Mack1; Bimston, David1, Golding, Allan1; Edwards, Courtney1; Nathan, Pinnar2 1 Department of Endocrine Surgery, Memorial Health System, Hollywood, FL 2 Department of Pathology, Memorial Health System, Hollywood, FL   Background/ Purpose: Afirma GEC molecular analysis was deployed by Veracyte in 2011 as a negative predictive value test to reduce the number of indeterminate thyroid cytology patients who require surgical interventions. Multiple studies indicate that the Afirma GEC has been effective in reducing unnecessary thyroid surgery, but evaluations of Afirma false negative nodules are less discussed in the literature because, by definition, most of these patients are not taken to surgery for definitive pathologic diagnosis. Methods: To address this issue, we have interrogated our community endocrine surgical experience regarding Afirma false negative nodules from 1/2011-2/2017. Results: Thirteen false negative Afirma GEC nodules in 13 surgical patients were identified out of a total of  524 Afirma GEC’s, 202 of which were benign (38.5%). Our minimum Afirma GEC false negative rate was 13 out of 202 or 6.4%.  Two of the 13 false negative GEC patients had conventional papillary thyroid cancer- the first only 4 mm in size and the second a 3 cm cystic papillary carcinoma.  The remaining 11 patients all had encapsulated or circumscribed follicular tumors including: 3 partially encapsulated follicular variant of papillary thyroid cancers (FVPTC), 3 circumscribed FVPTC’s, 3 encapsulated FVPTC’s, one follicular thyroid carcinoma and one Hurthle cell carcinoma.   None of the circumscribed or encapsulated FVPTC’s met criteria for non-invasive follicular tumors with papillary like features (NIFTP) on retrospective pathologic review. Conclusion: In our practice, Afirma GEC has a minimum false negative rate of 6.4%, consisting almost exclusively of encapsulated or circumscribed follicular tumors that are not NIFTP’s on retrospective review.   References:
    1. J Clin Endocrinol Metab. 2013 Apr;98(4):E761-8. doi: 10.1210/jc.2012-3762. Epub 2013 Mar 8. Does addition of BRAF V600E mutation testing modify sensitivity or specificity of the Afirma Gene Expression Classifier in cytologically indeterminate thyroid nodules? Kloos RT1, Reynolds JD, Walsh PS, Wilde JI, Tom EY, Pagan M, Barbacioru C, Chudova DI, Wong M, Friedman L, LiVolsi VA, Rosai J, Lanman RB, Kennedy GC.
    2. Diagn Cytopathol. 2016 Nov;44(11):867-873. doi: 10.1002/dc.23559. Epub 2016 Aug 18. Usage trends and performance characteristics of a “gene expression classifier” in the management of thyroid nodules: An institutional experience. Samulski TD1, LiVolsi VA2, Wong LQ2, Baloch Z2.
    3. Thyroid. 2012 Oct; 22(10): 996–1001.  The Impact of Benign Gene Expression Classifier Test Results on the Endocrinologist–Patient Decision to Operate on Patients with Thyroid Nodules with Indeterminate Fine-Needle Aspiration Cytopathology Daniel S. Duick,1 Joshua P. Klopper,2 James C. Diggans,3 Lyssa Friedman,3 Giulia C. Kennedy,3 Richard B. Lanman, 3 and  Bryan McIver4


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