Introduction. Currently, there are conflicting data regarding the effect of the c.470T> C germline mutation in the CHEK2 gene on increasing the risk of breast cancer (BC), so it is necessary to conduct research on large samples of patients, including in the Russian population, in order to analyze the contribution of this mutation to the risk of cancer developing.The aim of the study was to determine the frequency of occurrence of the genetic variant c.470Т>С in the CHEK2 gene in the Russian population in patients with BC and patients with benign breast diseases (BBD) to assess the possible effect of this deoxyribonucleic acid damage on the likelihood of cancer occurrence.Materials and methods. The study included 2,787 patients with BC and 1,004 patients with BBD who underwent examination and treatment at the Russian Scientific Center of Roentgenoradiology of the Ministry of the Russian Federation from 2010 to 2018. Molecular genetic study was carried out by real-time polymerase chain reaction to determine the characteristic of the Russian population hereditary genetic variant c.470Т>С in the CHEK2 gene using a diagnostic panel that allows to determine three germline mutations: c.1100delC, c.444+1G>A and c.470Т>С in the CHEK2 gene.Results. In patients with BC the frequency of the mutation c.470T>C in the CHEK2 gene was 3.8 %, in patients with BBD this mutation was detected in 4.7 % of cases. The frequency of the genetic variant c.470T>C in high-risk groups was: 5.1 % – for BC patients with clinical signs of hereditary disease and 4.9 % – for patients with BBD with a family history of cancer. There were no statistically significant differences between the frequency of the mutation c.470T>C in the general groups of BC patients and patients with BBD and the corresponding frequency in the high-risk groups, as well as in the groups of BC patients and patients with BBD (p >0.05).Conclusion. The results of this study indicate the probable absence of a relationship between the presence of the mutation c.470Т>С in the CHEK2 gene and an increased risk of BC.

"Standard" diagnostic panels allow identification of only a few of BRCA1 and BRCA2 gene mutations most common in a population. Therefore, tests relying on such panels may return false negative results, since the coding regions of these genes may have other defects. For breast cancer (BC) patients, false negative test results may translate into selection of inadequate therapy by their doctors. This study aimed to identify the features of BRCA-associated breast cancer in the population of the Russian Federation. The study included breast cancer patients (n = 4440). At the first stage, all patients were screened for the eight most common BRCA1 and BRCA2 genes mutations with the help of real-time PCR. Next, patients that exhibited clinical signs of a hereditary disease (CSHD) in the absence of common mutations (n = 290) had the entire coding regions of BRCA1 and BRCA2 genes studied with next generation sequencing (NGS). "Standard" mutations in the BRCA1 and BRCA2 genes were identified in 169 (3.8%) cases. In the CSHD group, such mutations were revealed in 15.4% of cases. NGS uncovered 33 rare pathogenic BRCA1 and BRCA2 gene mutations in 40 out of 290 breast cancer patients (13.8%). It was concluded that among the residents of the Russian Federation, the range of pathogenic variants of BRCA-associated breast cancer is wide, and it stretches beyond the mutations considered by the "standard" diagnostic panels. Analysis of the entire coding regions of BRCA1 and BRCA2 genes allows increasing efficiency of detection of germline mutations in breast cancer patients at least twofold.

Ispol'zovanie «standartnyh» diagnosticheskih panelej, dayushchih vozmozhnost' opredelyat' lish' neskol'ko naibolee rasprostranennyh v populyacii mutacij v genah BRCA1 i BRCA2, mozhet privodit' k poyavleniyu lozhnootricatel'nyh rezul'tatov iz-za nalichiya drugih povrezhdenij v kodiruyushchih oblastyah dannyh genov, chto, v svoyu ochered', mozhet privesti k neadekvatnomu vyboru taktiki lecheniya u bol'nyh rakom molochnoj zhelezy (RMZH). Cel'yu raboty bylo vyyavit' osobennosti BRCA-associirovannogo raka molochnoj zhelezy v rossijskoj populyacii. V issledovanie voshli pacienty s diagnozom RMZH (n = 4440). Na pervom etape metodom PCR v real'nom vremeni provedeno skriningovoe issledovanie vsekh pacientov na nalichie vos'mi naibolee rasprostranennyh mutacij v genah BRCA1 i BRCA2. Dalee pri nalichii u pacientov klinicheskih priznakov nasledstvennogo zabolevaniya (KPNZ) i otsutstvii rasprostranennyh mutacij (n = 290) provodili issledovanie vsej kodiruyushchej chasti genov BRCA1 i BRCA2 metodom sekvenirovaniya novogo pokoleniya (NGS). V 169 sluchayah (3,8%) byli vyyavleny «standartnye» mutacii v genah BRCA1 i BRCA2. V gruppe pacientov s KPNZ chastota vyyavlennyh «standartnyh» mutacij sostavila 15,4%. Metodom NGS u 40 iz 290 bol'nyh RMZH (13,8%) byli obnaruzheny 33 redkie patogennye mutacii v genah BRCA1 i BRCA2. Sdelan vyvod, chto BRCA-associirovannyj RMZH v rossijskoj populyacii harakterizuetsya shirokim spektrom patogennyh variantov, kotoryj ne ogranichen mutaciyami, vklyuchennymi v standartnye kliniko-diagnosticheskie paneli. Analiz vsej kodiruyushchej chasti genov BRCA1 i BRCA2 pozvolyaet povysit' effektivnost' vyyavleniya germinal'nyh mutacij u bol'nyh RMZH po krajnej mere v 2 raza.

Background: About 30% of cases of hereditary breast cancer (BC) are associated with the BRCA1 and BRCA2 gene mutations. The absence of the programs of mandatory genetic screening for hereditary BRCA-associated BC in Russia, as well as of an algorithm for molecular genetic testing does not allow fully accomplishing the necessary preventive, diagnostic and medical measures.Aim: To elaborate an algorithm for molecular genetic testing of BC patients in order to improve the efficacy of identification of the hereditary nature of the disease.Materials and methods: The study is based on the analysis of the results of molecular genetic testing of 3826 BC patients aged from 22 to 90 years, who were examined and treated in the Russian Research Center of Roentgenoradiology (Moscow) from 2010 to 2016. At the first stage of the study, germinal mutation in the BRCA1 and BRCA2 genes prevalent in the Russian population were identified by the real-time polymerase chain reaction (PCR). At the second stage, we searched for rare genetic variants of these genes by the ‘next generation sequencing’ (NGS) method.Results: The real-time PCR (the first stage) showed that the prevalence of the most typical for the Russian population mutations in the BRCA1 gene, associated with BC risk, was 3.5% (132/3826 BC patients). No carriers of the BRCA2 mutations were identified. Based on the analysis of a questionnaire survey and primary medical documentation, a group of 717 patients was selected from the total cohort, who had clinical features of the hereditary disease (CFHD). In this group, the BRCA1 and BRCA2 gene mutations were found in 126 patients (17.6%). At the second stage, a group of 193 patients with CFHD and no BRCA1 and BRCA2 mutations prevalent in the Russian population was investigated by NGS. Rare pathogenic mutations of these genes were found in 27 patients (14%). In total, it may be concluded that at least 30% of the BC patients with CFHD have germinal mutations in the BRCA1 and BRCA2 genes. Based on the data obtained, we have developed the algorithm of molecular genetic testing of BC patients aimed at identification of the hereditary nature of the disease.Conclusion: The high frequency of mutations in the BRCA1 and BRCA2 genes found in this study in BC patients with CFHD confirms the necessity of genetic testing for this hereditary disease. The information on its hereditary nature allows for the introduction of essential therapy modification with a personalized approach. Regular follow-up of patients with hereditary BC and prevention of new BC cases and other cancers (ovarian, gastric, pancreatic and prostate cancer, as well as melanoma) in their relatives with BRCA1 and BRCA2 mutations have to be implemented by a multidisciplinary team (specialists in mammology, gynecology, oncology, medical genetics, chemotherapy and psychotherapy).

Background: Next generation sequencing has a potential to revolutionize the management of cancer patients within the framework of precision oncology. Nevertheless, lack of standardization decelerated entering of the technology into the clinical testing space. Here we dissected a number of common problems of NGS diagnostics in oncology and introduced ways they can be resolved.Methods: DNA was extracted from 26 formalin fixed paraffin embedded (FFPE) specimens and processed with the TrueSeq Amplicon Cancer Panel (Illumina Inc, San Diego, California) targeting 48 cancer-related genes and sequenced in single run. Sequencing data were comparatively analyzed by several bioinformatics pipelines.Results: Libraries yielded sufficient coverage to detect even low prevalent mutations. We found that the number of FFPE sequence artifacts significantly correlates with pre-normalization concentration of libraries (rank correlation -0.81; p < 1e-10), thus, contributing to sample-specific variant detection cut-offs. Surprisingly, extensive validation of EGFR mutation calls by a combination of aligners and variant callers resulted in identification of two false negatives and one false positive that were due to complexity of underlying genomic change, confirmed by Sanger sequencing. Additionally, the study of the non-EGFR amplicons revealed 33 confirmed unique mutations in 17 genes, with TP53 being the most frequently mutated. Clinical relevance of these finding is discussed.Conclusions: Reporting of entire mutational spectrum revealed by targeted sequencing is questionable, at least until the clinically-driven guidelines on reporting of somatic mutations are established. The standardization of sequencing protocols, especially their data analysis components, requires assay-, disease-, and, in many cases, even sample-specific customization that could be performed only in cooperation with clinicians.

The overwhelming majority of cases of hereditary breast cancer are associated with mutations in the BRCA1 and BRCA2 genes. The search for only the BRCA1/2 founder mutations in the Russian population may lead to a number of false-negative results due to the presence of rare genetic damage in these genes. The aim of this study was to search for rare BRCA1 and BRCA2 mutations associated with risk of breast cancer. For this study using neхt-generation sequencing (NGS), a group of 193 breast cancer patients was formed. Results of this research showed that the range of pathogenic variants in BRCA1/2 associated with risk of breast cancer is characterized by a big variety and not limited only to mutations, widespread in the Russian population. As a result of the study, 22 rare heterozygous pathogenic mutations were found in 27 breast cancer patients (14%). Variants with unknown clinical significance in BRCA1/2 , which could be one of the causes of the breast cancer disease, were found in 6 patients. On the basis of our obtained data on rare mutations frequency (14%) and also founder mutations frequency in the group of patients with clinical signs of a hereditary disease in the Russian population (17,6%) it is possible to say with confidence that about 32% breast cancer cases in the group of patients with clinical signs of a hereditary disease were associated with BRCA1/2 mutations.

The software-hardware system for comet assay analysis used for estimation of cell radiosensitivity of cancerl patients is described. Initial radiation-induced DNA damage and kinetics of DNA repair in leukocytes from 22 patients of radiosurgical department of RNCRR before radiotherapy, was assessed using alkaline comet assay after exposure to 5 Gy of gamma rays in vitro. The cytogenetic analysis for this group of patients was performed in lymphocytes irradiated in vitro at G0 stage with dose 2 Gy The association between parameters of cells radiosensitivity and acute side reactions to radiotherapy (radiation enterocolitis and cystitis) was evaluated.