American Association of Clinical Endocrinoligist's (AACE) 23rd Annual Scientific and Clinical Congress:

Medullary Thyroid Carcinoma Detection: Novel Gene Expression Classifier

Medullary thyroid carcinoma (MTC) is a rare, yet very aggressive thyroid cancer that is difficult to detect preoperatively. In more than half of the cases, cytology does not identify MTC and serum calcitonin tests have high false-positive rates.

During the 23rd Annual Scientific and Clinical Congress of the American Association of Clinical Endocrinology, EndocrineWeb spoke with Dan Pankratz, PhD during his poster presentation, Analytical Performance of a Gene Expression Classifier for Medullary Thyroid Carcinoma. Dr. Pankratz stated, “Medullary thyroid cancer is a rare and aggressive neoplasm, and about 2.2% of all thyroid cancers are MTCs. The subject of our study is a molecular gene expression classifier that detects medullary thyroid cancer.”

Challenge: Identify MTC Prior to Surgery
Dr. Pankratz explained that the recommended treatment for MTC is different than for standard nodules suspicious for thyroid cancer. Those patients may undergo partial thyroidectomy. However, when MTC is suspected, the patient typically undergoes a total thyroidectomy with lateral neck dissection to remove possible metastases to the lymph nodes. “The challenge has been to identify patients with MTC before going to surgery,” stated Dr. Pankratz. Unfortunately, the standardized pathological approaches are not very sensitive to detecting MTC; in fact, they fail to detect MTC about 50% of the time.

Study Methodology
Dr. Pankratz and his colleagues developed a molecular test designed to be performed on the fine-needle aspiration biopsy (FNAB) obtained preoperatively. “Our methodology involved a simulation. We assessed assay response to modeled mixtures of MTC samples with normal thyroid tissue, a benign thyroid nodule, a Hürthle cell adenoma, and whole blood. We also analyzed the MTC classifier's performance on 27 histopathologically confirmed MTC tissues and clinically collected FNABs.” stated Dr. Pankratz.

Results and Conclusions

  • 26 of 27 specimens correctly identified MTC (96.3% sensitivity)
  • Tolerance to assay RNA input variation (5-25ng) and genomic DNA contamination (30% by mass) was demonstrated with 100% accuracy under all tested conditions.1
  •  Mixture modeling of MTC samples with benign thyroid tissues and blood showed detection of MTC a majority of the time at MTC sample proportions as low as 20%.1
  •  Results were reproducible within and across processing runs and between laboratories.1

Reference

  1. Pankratz D, Hu Z, Kim SY, Monroe R, Wong M, Diggans J, et al. Analytical Validation of a Gene Expression Classifier for Medullary Thyroid Cancer. Abstract #1109. Presented at the American Association of Clinical Endocrinologists 23rd Annual Scientific and Clinical Congress, Las Vegas, NV. May 14-18, 2014.
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