Implementation of molecular genetic tests in the diagnostics of thyroid cancer: own research

Abstract

Aim — to investigate the significance of BRAFV600E, NRAS, KRAS, HRAS, RET/PTC (RET/PTC1 and RER/PTC3), PAX8/PPARg mutations for the development and course of thyroid cancer with the determination of a significant predictor mutation. Materials and methods. The analysis included 63 selected case histories of patients who, at the preoperative stage, underwent molecular genetic testing (MHT) of the thyroid gland (TG) masses and subsequently underwent surgical treatment in the surgical department of the Ukrainian Scientific and Practical Center for Endocrine Surgery, Transplantation of Endocrine Organs and Tissues. The average age of the patients was 41.0 ± 1.8 years; from them 7men and56women. All patients underwent fine-needle aspiration puncture biopsy(FNAB) of thyroid nodules according to the standard method followed by a cytological conclusion in accordance with the Bethesda system.The Bethesda III category was revealed in 3 patients (4.8 %), Bethesda IV — 13 patients (20.6 %), Bethesda V — 12 patients (19.0 %), Bethesda VI in 35 (55.6 %) patients. The pathogenic mutations were detected in 47 (74.6 %) patients (group 1), among them two mutations were simultaneously found in two subjects. In 16 cases (25.4 %), no pathogenic mutation was found at all (group 2). Results. The genes that occurred most often were BRAFV600E — in 35 patients (55.6 %), NRAS — in 11 patients (17.5 %), KRAS — in 3 patients (4.8 %). In case of thyroid cancerdiagnosis, pathogenic mutations were found in 38 (79.1 %) subjects. The BRAFV600E gene mutation was observed when establishing a cytological conclusion classified as Bethesda III—V in 28.9 %, and in Bethesda V and in 77.1 %. Accordingly, the sensitivity of the test was low — 0.646, specificity — 0.733. The high prognostic significance of a positive result(PPV) value (from 0.784 to 0.943) indicated the likelihood of detecting thyroid cancer. This assumption confirms the calculation of the c-square criterion with the Yates correction, which is 5.207 (p = 0.023). The use of this test for the presence of the NRAS gene to detect thyroid cancer was ineffective, the value of the c -square criterion with Yates correction = 0.009 (p = 0.927). The incidence of thyroid cancer in group 1 in the cytological class Bethesda III—V was higher than in group 2, but it did not differ significantly between the groups. The aggressiveness of thyroid cancer in patients of group 1 with a positive MHT result did not have significant differences compared with the results obtained in group 2 (39.5 % and 33.3 %, respectively). Conclusions. The use of the kit for the determination of MHTmade it possible to identify pathogenic mutations in the genes BRAFV600E, NRAS, KRAS in 79.1 % of cases. The presence of these genes in combination with the analysis of cytomorphological findings classified according to the Bethesda III—V system did not increase the detection of thyroid cancer in the studied patients. The BRAFV600E gene, which was observed in 64.6 % of cases (PPV from 0.784 to 0.943), was a significant predictor among the studied candidate genes for establishing the diagnosis of thyroid cancer. Detection of a pathogenic mutation in patients with thyroid cancer did not indicate in favour of its aggressive course.