Targeted next-generation sequencing of cancer-related genes in thyroid carcinoma: A single institution's experience

Thyroid carcinoma (TC) has characteristic genetic alterations, including point mutations in proto-oncogenes and chromosomal rearrangements that vary by histologic subtype. Recent developments in next-generation sequencing (NGS) technology enable simultaneous analysis of cancer-associated genes of interest, thus improving diagnostic accuracy and allowing precise personalized treatment for human cancer. A total of 50 patients who underwent thyroidectomy between 2014 and 2016 at Hokuto Hospital were enrolled. Total DNA was extracted from formalin-fixed, paraffin-embedded tissue sections and quantified. Targeted regions of 24 cancer-associated genes were amplified by PCR, barcoded and sequenced using an Illumina MiSeq platform. Subjects included 30 patients with papillary carcinoma (PC), two with PC tall cell variant (TVPC), two with PC follicular variant (FVPC), eight with follicular carcinoma, seven with poorly differentiated carcinoma (PDC), and one with anaplastic carcinoma (AC). The BRAF V600E mutation was present in 25 of 30 (83%) patients with PC, 2 of 2 (100%) patients with TVPC, 6 of 7 (86%) patients of PDC, and one patient with AC. PIK3CA mutations were present in 3 of 30 (delPV104P, A1046T and C420R; 10%) patients with PC and 1 of 7 (H1047R; 14%) patients with PDC. The TP53 mutation was present in 1 of 30 (R306*; 3.3%) patients with PC and 1 of 7 (Q152*; 14%) patients with PDC. The NRAS mutation was present in 1 of 2 (Q61K, 50%) patients with FVPC. Statistical analysis showed that patients without the BRAF V600E mutation had advanced pathologic T and N stages compared with those with the mutation (P=0.047 and P=0.019, respectively). The BRAF V600E mutation was not correlated with overall and disease-free survival in patients with PC. A patient with PC with a mutation in EGFR (K852Q) and the PIK3CA mutation had an aggressive course with multiple bone and lung metastases. Detection of mutations in cancer-associated genes using NGS could enhance the understanding of the clinical behavior of TC.