Molecular Test Effectively Guides Extent of Initial Thyroidectomy

The routine use of a molecular testing panel increases the likelihood of performing the correct initial surgery for patients with thyroid nodules and cancer.

A clinical algorithm using routine cytological molecular testing (MT) promotes initial total thyroidectomy (TT) for clinically significant thyroid cancer (sTC) and/or correctly limits surgery to lobectomy when appropriate. Either TT or lobectomy is often needed to diagnose differentiated thyroid cancer and determining the correct extent of initial thyroidectomy is challenging.

Scientists at the University of Pittsburgh Medical Center (Pittsburgh, PA, USA) conducted a single-institution cohort study of 671 patients with nonmalignant cytology who had thyroidectomy between October 2010 and March 2012. Cytological diagnosis was made using the 2008 Bethesda criteria, and one or more indications for thyroidectomy. The patients who received biopsies all had suspicious thyroid nodes.

Approximately half the biopsy samples were run through the molecular panel, and the other half were not. Patients whose tissue samples were not tested with the panel had a 2.5-fold higher statistically significant likelihood of having an initial lobectomy and then requiring a second operation. Using a routine algorithm for prospective MT, the team demonstrated that the likelihood of optimal initial thyroid surgery is increased by the reflexive use of testing a molecular marker panel of proto-oncogene B-Raf (BRAF), Rat sarcoma (RAS), Paired box gene 8- peroxisome proliferator-activated receptor γ 1 (PAX8-PPARγ), and Rearranged in Transformation/Papillary Thyroid Carcinomas (RET-PTC) on fine needle aspiration biopsy (FNAB) specimens.

By analyzing new data from a single institution that has been prospectively and routinely using FNAB-MT since 2007, the investigators observed that, overall, FNAB-MT facilitated a 30% increase in the appropriate use of initial TT for sTC histology and a 33% increase in the appropriate use of initial lobectomy for non-sTC histology. Yuri Nikiforov, MD, PhD, a professor of pathology and coauthor of the study said, “We're currently refining the panel by adding tests for more genetic mutations, thereby making it even more accurate. Thyroid cancer is usually very curable, and we are getting closer to quickly and efficiently identifying and treating all cases of thyroid cancer.” The study was published in July 2014 issue of the Annals of Surgery.

Related Links:
University of Pittsburgh Medical Center