ИСТИНА

Background & Objectives: Despite widespread use of cytologic screening, the incidence of cervical adenocarcinoma has been increasing in recent years. This histologic subtype is characterized by a poor prognosis and immunotherapy is the promising therapeutic strategy. Microsatellite instability (MSI) is one of the key biomarkers to predict response to immune checkpoint inhibitors, but some data have been accumulated on the frequency of MSI among cervical adenocarcinomas. The aim of this work is to investigate the incidence of MSI in cervical adenocarcinoma as it may reveal new therapeutic strategies to improve patient prognosis. Methods: Surgical specimens were collected from 38 patients with cervical adenocarcinoma. Immunohistochemistry for MSH2 (FE-11), MSH6 (EP-49), PMS2 (EP-51) and MLH1(ES05) (Dako, Agilent Technologies, USA) was performed on 3-mm thick sections of a representative formalin-fixed, paraffin-embedded (FFPE) tumor tissue using PrimeVision detection system (PrimeBioMed LLC, Russia) in Autostainer 480S immunostainer (ThermoFisherScientific, USA). DNA was isolated from FFPE tumor tissue by phenol-chloroform extraction using a DNA extraction kit (BioLink LLC, Russia). PCR followed by fragment analysis of PCR products by capillary electrophoresis was used as a reference method with application of the reagent kit “COrDIS MSI” (BioLink LLC, Russia) according to the manufacturer's instructions. PCR was performed on the amplifier “BIS” M111-02-96 (NovosibBioPribor LLC, Russia). Fragment analysis was performed according to the GeneMapper manual for Applied Biosystems 3500 genetic analyzer (ThermoFisherScientific, USA). Results: The incidence of MSI in cervical adenocarcinoma was 10,5% (4/38) when analyzed by immunohistochemistry and 13,1% (5/38) when analyzed by molecular technique (the concordance of the two methods was 98,2%). Conclusion: MSI in cervical adenocarcinoma is not a common event. The introduction of MSI assay into clinical practice may help to identify a limited group of patients who will benefit from immunotherapy. Both immunohistochemical and molecular technique may be considered depending on the capabilities of the particular laboratory.