Purpose: To describe the genetic landscape and clinical characteristics of Chinese patients diagnosed with papillary thyroid cancer (PTC) and to determine which high-risk genetic characteristics suggest a likelihood of lymph node metastasis (LNM) and lateral lymph node metastasis (LLNM).
Patients and Methods: Data from previously untreated patients with PTC collected between May 2018 and December 2020 from 14 hospitals in China were analyzed retrospectively. High-risk pathologic characteristics were defined as T3/T4, N(+), and N1b(+) stages. All patients were tested for 57 genes by second-generation sequencing. The t -test, chi-square test, and Fisher’s exact test were performed for statistical analysis.
Results: Overall, 395 patients were enrolled in this study. The prevalence of BRAF mutation was 78.53%. BRAF mutant allele frequency (MAF) > 16.93% was associated with a significantly higher risk of LNM, LLNM, and T3 + T4 stage compared with a low-risk group, defined by a MAF < 2.54% (odd ratios [ORs] for each risk=3.38, 3.46, and 8.54, respectively), and an intermediate-risk group, defined by a MAF of 2.54% to 16.93% (ORs=2.04, 2.07, and 4.07, respectively). The population with RET fusion had higher T, N, and N1b stages (ORs for each stage=10.40, 7.60, and 8.77, respectively) compared with a RET -negative population. Similar conclusions about T, N, and N1b stages were observed in relation to multiple driver gene mutations (ORs for each stage=7.48, 2.80, and 7.04, respectively) compared with population without multiple driver mutations. These genetic characteristics may be suggestive of high clinical risk. However, regardless of genetic profiles, patients younger than age 45 years had greater rates of LNM and LLNM.
Conclusion: The main driver gene in this study, BRAF , differs significantly between the United States (79% vs 51%) and other countries. The Chinese population in this study that experienced more aggressive tumor biology had a BRAF MAF greater than 16.93%, exhibited RET fusion events, and had multiple driver gene mutations; thus, these traits may be considered high-risk genetic characteristics in PTC that could warrant aggressive treatment in such population.
Keywords: papillary thyroid cancer, lymph node metastasis, high risk clinicopathological characteristics, genotypes