BRAF MUTATION GUIDES THERAPY OF NODULES WHEN CYTOPATHOLOGY IS INDETERMINATE

SUMMARY BACKGROUND AND METHODS In Korea, more than 90% of well-differentiated thyroid cancer is papillary, and the BRAFV600E mutation is found in more than 80%, higher percentages than what are found in many Western countries. Over the 2-year period beginning in March 2007, the cytopathology in 865 fine-needle aspiration biopsies (FNAB) of thyroid nodules was prospectively analyzed at Konkuk University in Seoul using the 2008 National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Guidelines. The cover slips were then removed from the slides and “atypical cells of interest” were scraped and DNA was extracted and analyzed for the BRAFV600E mutation using polymerase chain reaction (PCR) with a biotinylated primer, purification with streptavidin–agarose and pyrosequencing. RESULTS In the 504 FNABs that were read as being “benign,” no BRAFV600E mutants were found. The mutation was found in 32% of the 141 samples read as “atypical cells of undetermined significance” (ACUS), in 85% of the 54 samples read as “suspicious for malignancy,” in 92% of the 140 samples read as “malignant,” and in 10% of the 10 samples read as “suspicious for follicular neoplasm.” BRAF status could not be assessed on 16 FNABs with insufficient material for cytopathologic assessment.