Detection of BRAF V600E mutation in fine-needle aspiration fluid of papillary thyroid carcinoma by droplet digital PCR.

OBJECTIVES: Papillary thyroid carcinoma (PTC) accounts for 85% of thyroid carcinoma, which is the most common endocrine tumor. For the diagnosis of PTC, ultrasound-guided fine needle aspiration (FNA) with pathological evaluation is the standard test and BRAF V600E mutation is the most common molecular marker associated with the occurrence, progression and poor clinicopathological characteristics of PTC. However, because of the small amount of the tumor cells obtained by FNA for pathological evaluation or BRAF V600E mutation detection, more sensitive and accurate methods are required. Our study aimed to investigate the performance of droplet digital PCR (ddPCR) in detecting BRAF V600E mutation in FNA samples from PTC patients. METHODS: One hundred and sixty suspected thyroid cancer patients were enrolled, including 146 PTC patients, 2 follicular thyroid carcinoma (FTC) and 12 benign patients, identified by FNA biopsy according to the NCCN clinical practice guidelines of Thyroid Carcinoma. ddPCR and amplification-refractory mutation system (ARMS, AmoyDx) were used to detect BRAFV600E mutation and the results were compared. RESULTS: ddPCR had high reproducibility (CV0.1% = 22.82% and CV10% = 4.85%) and the detection sensitivity can reach 1­2 copies/µl (0.01%). Among the 160 patients, 128 BRAF V600E mutations were detected, including 4 ARMS negative patients and 3 benign cases [corrected]. CONCLUSIONS: Our results demonstrated that ddPCR could be used in detecting BRAF V600E mutation from FNA fluid samples with higher sensitivity and accuracy than ARMS.