Comparison of the Clinical Validity of Droplet Digital PCR to ARMS‐PCR for BRAF V600E Mutation Detection in Thyroid Nodules

Objectives Droplet digital PCR (ddPCR) has been reported to have a superior validity over PCR with amplification‐refractory mutation system (ARMS‐PCR) for detecting the BRAF V600E mutation in thyroid nodule fine‐needle aspiration (FNA) samples using cytological diagnosis as the reference. However, the added value of ddPCR on surgical decision‐making remains to be illustrated when the technique is combined with FNA cytology. Methods A total of 277 consecutive patients with thyroid nodules were subjected to FNA cytology and BRAF V600E testing with ARMS‐PCR. Within this patient cohort, 90 patients underwent surgical intervention with pathological diagnosis available. BRAF V600E testing with ddPCR was performed retrospectively using FNA frozen DNA specimens. The clinical validity and utility of ddPCR in comparison with ARMS‐PCR were compared using surgical pathology as the reference. Results Overall, 101 BRAF V600E mutations were detected by ddPCR, including five ARMS negative patients, four of whom were confirmed to have papillary thyroid cancer (PTC) by surgical pathology. Of the 90 patients with surgical pathology, which is considered the gold standard, ddPCR BRAF V600E testing yielded a sensitivity of 91.3% and specificity of 100% for PTC diagnosis, higher than that of ARMS (sensitivity 83.1%, specificity 100%). However, ddPCR only identified one more candidate patient for surgical intervention than ARMS when the techniques were combined with cytology. Conclusions This study highlighted the superior performance of ddPCR over ARMS in BRAF V600E detection from thyroid nodule FNA samples. Further studies are needed to evaluate the cost‐effectiveness of replacing ARMS‐PCR with ddPCR for surgical decision‐making. The MicroDrop‐100TM ddPCR system was able to detect the BRAF V600E mutation. In the representative 2‐dimention figure, the X‐axis represents the wild‐type signals (HEX) while the Y‐axis represents the mutant signals (FAM). The black points on the plot represents the negative droplets, the green points represents the droplets that are positive for wild‐type DNA only, the blue points represents the droplets that are positive for mutant DNA only, and the orange points represents the droplets that are positive for both wild‐type and mutant targets.