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

Abstract

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. 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. 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. 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.