MOLECULAR TYPES IN THE PROGNOSIS OF PAPILLARY THYROID CANCER BASED ON THE ANALYSIS OF THE STATUS OF BRAF V600E, INDEX AND KI-67 EXPRESSION

The aim of our research was to determine the possibilities to stratify patients with papillary thyroid cancer (PTC) on the group’s forecast, depending on the status of the mutation BRAF v600e and Ki-67 expression. The study included 89 PTC patients with the known prognosis for the period of 2005-2015. They were treated in the Altai regional oncology center and underwent surgery for PTC over the period of 2005-2013. Mutation p. Val600Glu (V600E) BRAF gene was determined with the use of allele-specific real-time PCR kit «Real-time-PCR-BRAF-V600E («BioLink»)». Immunohistochemical examination was performed with antibodies Ki-67 (clone MIB1, «DAKO») on stainer «Ventana XT» according to standard protocols. We revealed BRAF V600E not to be an independent predictor. Different variants of PTC, depending on the level of expression of Ki-67 in combination with a mutation of BRAF V600E was allowed to identify 3 groups of molecular types of PTC: a lack of mutation and a low Ki-67 (type I), with mutation and a low Ki-67 (type II) and with the presence and/or absence of a mutation and high level Ki-67 (type III). I molecular type PTC is the most favorable from the point of view of survival: 100% of patients live 10 years. Molecular type II is characterized by an intermediate prognosis: 76% of patients lived out up to 10 years. Molecular type III is characterized by the poor prognosis: only 36.8 percent of cases lived up to 10 years. In multivariate analysis of survival in PTC patients the independent prognostic factor happened to be the molecular type of tumor. In this case χ2 = 35 at p ≤ 0.000005.