CORRELATION OF KI67 PROLIFE-RATION INDEX AND THE LEVEL OF METABOLIC ACTIVITY OF THE OROPHARYNGEAL TUMOURS

The objective of this study was to compare the positron emission tomography with CT (PET-CT) and histological, immunohistochemical tests (IHCT) for squamous-cell carcinoma of differing degrees of differentiation (G1-G3), with the subsequent determination of new criteria for identifying the level of differentiation of tumors. Methods. The methods of biostatistics were used when analyzing the results of the study. In order to compare the indicators in three groups, the Kruskal-Wollis criterion was used, in the a posteriori comparisons - the criterion of Dunn's multiple comparisons. In all cases, the critical level of significance is taken as αcrit=0.05. To analyze the prognostic characteristics of the test for marker Ki67, we used a method of building and analyzing operating characteristic curves (ROC curves). The adequacy of the test was evaluated by the area under the ROC curve (AUC), and its 95% confidence interval is given. The optimal decision threshold for the test was calculated using the YoudenInex = Max (test sensitivity + test specifics - 100%), and the prognostic test characteristics at the selected threshold were evaluated according to the sensitivity index (95% confidence interval) and the specifics (95% confidence interval) of the test. The analysis was based on the MedCalcv.16.8 statistical package (MedCalcSoftWarebvba, 1993-2016). Research results. Squamous-cell carcinomas of the oropharyngeal region are epithelial tumors of epithelial origin, with diffuse or spotted growth, eosinophilic cells, nuclear polymorphism, focuses of concentrically cast-off epithelium. The tissue of the tumor can have a wide variety of mitoses and dyskeratosis. The study involved 121 patients divided into groups. According to the results of our study, it has been statistically proved that the IHC test method using monoclonal antibodies to Ki67 can be used to predict the degree of differentiation of squamous cell carcinoma of the oropharyngeal region. It is recommended to set the critical value of the Ki67 at 50% level in order to predict the high or low degree of tumor differentiation. In the case when Ki67 score is higher than 50%, the specificity and sensitivity of the test to predict the low degree of tumor differentiation are 90.9% and 64.6% respectively. If, based on the results of the IHC test, the Ki67 score is less than 50%, the specificity and sensitivity of the test to predict the high degree of tumor differentiation is 62.7% and 75.9% respectively. The degree of differentiation of squamous cell carcinoma of the oropharyngeal segment is one of the factors that determine the proliferative potential of cancer and the five-year survival of patients. The main conclusion of our study is the confirmation of the effectiveness of the use of IHC test with an antibody to Ki67 and PET-CT for the diagnosis of squamous cell carcinoma of the oropharyngeal area and determination of the degree of its differentiation with a high level of sensitivity and specificity of both methods. The use of a combination of methods is recommended for increasing the reliability of the results and deepening of the preoperative data.