Afirma GSC: Early Endocrine Surgery Practice Performance 8/2017-2/2018


Interview with R. Mack Harrell, M.D., Integrative Endocrine Surgery, Memorial Health System, Boca Raton, FL

Dr. R. Mack Harrell is co-founder of the Memorial Center for Integrative Endocrine Surgery in Hollywood, Weston and Boca Raton, Florida. He is president of the American College of Endocrinology and past president of the American Association of Clinical Endocrinologists. Dr. Harrell’s practice began using the next-generation Afirma® Genomic Sequencing Classifier (GSC) for its thyroid nodule patients in August 2017, after using the Afirma® Gene Expression Classifier (GEC) for more than six years. At AACE 2018, Dr. Harrell presented findings from an analysis that compared the real-world performance of the two tests.

Q: What was the intention and focus of this analysis?

Dr. Harrell: As a fully integrated endocrine surgery practice, we perform a lot of thyroid surgeries and have a very extensive, detailed database of thyroid nodule clinical features, imaging, FNA results, molecular testing, final pathology and clinical outcomes. In fact, we’ve conducted Afirma testing on all thyroid nodule patients with indeterminate biopsy results for more than seven and a half years. So this puts us in a relatively unique position to be able to assess the real-world performance of the next-generation Afirma GSC in identifying benign nodules, as compared to that of the Afirma GEC test. Additionally, we were particularly interested to see if the Afirma GSC had improved accuracy among Hürthle-cell dominant specimens, which we identified in a 2014 Endocrine Practice article as a challenge with the earlier test. We used Afirma GEC test results for the period January 2011-July 2017 and compared them to Afirma GSC results for August 2017 to February 2018.

Q: Topline, what did you find?

Dr. Harrell: The findings were actually quite striking. We saw a dramatic increase in specificity with the next-generation Afirma GSC. Over the time frames assessed, the GSC identified approximately 51 percent more Bethesda 3 and 4 nodules as benign when compared with the GEC. Among the particularly challenging sub-set of nodules that were Hürthle-cell dominant – i.e., oncocytic biopsies – the next-generation test resulted in a 49 percent increase in the percentage of nodules classified as benign.

Q: How would you characterize these findings in terms of their relevance and importance to you as a treating physician?

Dr. Harrell: Using the Afirma GSC, we sent 19 percent fewer patients to surgery, including significantly fewer patients with Hürthle-cell dominant nodules. This improvement is very much appreciated by our patients.

Q: Based on your early experience with the Afirma GSC, what is your confidence in the accuracy of Afirma GSC benign calls?

Dr. Harrell: Preliminarily, we are very favorably impressed with the new Afirma GSC test. Over the next 6 to 12 months we look forward to reporting a more complete experience based on pathologic diagnoses with Afirma GSC patients who undergo surgical excisions.

Q: What is the next step in your research?

Dr. Harrell: We are planning careful clinical and ultrasonographic follow-up of those patients whose nodules were Afirma GSC benign to assess their outcomes and, therefore, the test’s long-term performance.