Abstract: Background and purpose: The incidence of papillary thyroid microcarcinoma (PTMC) has been increasing rapidly, and its treatment is controversial. Most of the key indicators of PTMC risk assessment are clinical and pathological parameters after operation, which are mainly based on retrospective review limiting guiding value for clinical treatment. The objective of this study was to analyze the correlation between the mutations of BRAF^V600E and telomerase reverse transcriptase (TERT) promoter and PTMC risk factors, and their value in the risk assessment of PTMC. Methods: This study retrospectively analyzed 107 cases of PTMC which were diagnosed after the surgery at the Department of Head and Neck Surgery in Gansu Province Tumor Hospital from October 2014 to June 2016. The mutations of BRAF^V600E and TERT promoter were detected by polymerase chain reaction (PCR) direct sequencing. We analyzed the data using χ2 test and binary logistic regression analysis. Results: Among 107 patients with PTMC, BRAF^V600E and TERT promoter mutation rates were 68.2% and 11.2%, respectively. Single factor analysis showed that the presence of membrane invasion and lymph node metastasis was significantly correlated with BRAF^V600E mutation (P<0.01). Age, gender, capsular invasion, poor pathologic subtype and lymph node metastasis were significantly correlated with TERT promoter mutation and BRAF^V600E and TERT mutation at the same time (P<0.05). Multifactorial analysis showed that the factors closely related to the BRAF^V600E mutation included capsular invasion (P=0.012) and lymph node metastasis (P=0.000). The following factors were closely associated with TERT promoter mutation: male (P=0.004), age<45 years (P=0.026), capsular invasion (P=0.004), pathological subtype (P=0.030) and lymph node metastasis (P=0.043). The following factors were closely related to the simultaneous mutations of BRAF^V600E and TERT: male (P=0.022), capsular invasion (P=0.023), poor pathological subtype (P=0.041) and lymph node metastasis (P=0.030). Conclusion: The risk of recurrence increases significantly when BRAF^V600E and TERT mutations occur simultaneously in PTMC and may have an adverse outcome. Combined detection of BRAF^V600E and TERT promoter mutations is of great value in risk assessment of PTMC. They have important value for the risk assessment of PTMC.

Key words: Papillary thyroid microcarcinoma, BRAF^V600E, Telomerase reverse transcriptase, Mutation, Risk assessment