The ratio of BRAFV600E alleles can be used to assess the biological behavior of papillary thyroid carcinoma

Abstract

Background The BRAFV600E mutations is an important molecular event in the occurrence and development of papillary thyroid carcinoma (PTC). A qualitative detection of the BRAFV600E mutation is still insufficient to explain the biological behavior of PTC. Though quantitative detection of the BRAFV600E mutation can reflect certain characteristics of PTC, its clinical value is still controversial. We aimed to investigate the association between the ratio of BRAFV600E alleles and clinicopathological parameters in PTC patients. Methods Genomic DNA was extracted from specimens obtained from 329 PTC patients undergoing thyroidectomy. The ratio of BRAFV600E alleles was determined by amplification refractory mutation system (ARMS) and droplet digital polymerase chain reaction (ddPCR). Inconsistent results were further verified by next-generation sequencing (NGS). The clinicopathologic features, clinical tumor stage, and tumor recurrence risk stratification of all patients were correlated with the ratio of BRAFV600E alleles. Results The sensitivity of ddPCR was superior to that of ARMS and almost the same as that of NGS. In total, 275 of 329 patients had the BRAFV600E mutation as determined by ARMS, ddPCR and NGS. The ratio of BRAFV600E alleles ranged from 0.17%-48.0%, with a median ratio of 12.58%, and significantly correlated with tumor size (p<0.001), capsule or extrathyroidal invasion (p<0.001), the number or rate of lymph node metastases (p<0.001), tumor stage (p=0.006) and tumor recurrence risk (p<0.001) but not with sex, age or multifocality. The ratio of BRAFV600E alleles was much lower in PTC patients with Hashimoto's thyroiditis than in those without (p<0.001). Conclusions The ratio of BRAFV600E alleles can reliably reflect the biological behavior of PTC, making it a molecular-based stratification index of recurrence risk. The quantitative detection of BRAFV600E has the potential to guide the clinical diagnosis and treatment of PTC.