Immunohistochemistry as an accurate tool for evaluating BRAF-V600E mutation in 130 samples of papillary thyroid cancer

Background: BRAF V600E mutation has been investigated by immunohistochemistry and has shown high sensitivity and specificity. We aim to investigate the accuracy of immunohistochemistry versus molecular testing of BRAF V600E in papillary thyroid cancer using a large number of polymerase chain reaction-positive BRAF V600E papillary thyroid cancer tissues. Methods: We stained 130 formalin-fixed papillary thyroid cancer specimens using the VE1 antibody: 100 BRAF V600E positive and 30 BRAF V600E negative confirmed by PCR. The sensitivity, specificity, and predictive values of the antibody were assessed. Results: Immunohistochemistry of BRAF V600E showed 98.0% sensitivity, 93.3% specificity, and positive and negative predictive values of 98.0% and 93.3%, respectively. Of 100 patients with BRAF V600E PCR-positive samples, 97 (97.0%) had cytoplasmic weak (4.0%), moderate (17.0%), and strong (76.0%) immunostaining. In BRAF V600E PCR-negative samples, cytoplasmic staining was not detected in 93.3% (28/30) of papillary thyroid cancer tissues. The receiver operating characteristic curve demonstrated a high validity and comparable immunohistochemistry method (area under the curve = 98.8%) compared with PCR testing. Conclusion: The use of VE1 immunohistochemistry for the detection of BRAF V600E in papillary thyroid cancer tissues is a clinically applicable method with high specificity, sensitivity, and positive and negative predictive values. The reliable use of BRAF V600E immunohistochemistry should promulgate the routine use of this method for BRAF V600E detection in papillary thyroid cancer tissues