В данном разделе указаны критерии оценки клинической значимости применения дорогостоящей противоопухолевой лекарственной терапии в соответствии со шкалой, разработанной экспертной группой (см. стр. 7). В тексте они обозначены, как магнитуда клинической значимости (МКЗ).

Today, the contribution of hereditary tumor syndromes to the development of cancer in children is obvious, which determines the need for screening programs and selection of the most effective methods of anticancer therapy. One of the most aggressive hereditary tumor syndromes is heritable TP53-related cancer syndrome (hTP53rc, formerly known as Li–Fraumeni syndrome), characterized by a high risk, early onset and recurrent cases of malignant neoplasms in one patient. The article describes current data on hTP53rc syndrome and the features of its clinical course, and provides international recommendations for monitoring and cancer screening in pediatric patients with hTP53rc syndrome. As a clinical observation, we present an analysis of the registry of patients with relapsed and refractory forms of medulloblastoma (n = 241) with the assessment of its incidence in cases of germline mutations in the TP53 gene with the description of their medical history and the influence of this genetic event on the outcomes. The results of our study, as well as data from international literature, indicate unfavorable prognosis in tumors, including medulloblastoma, in patients with hTP53rc syndrome, however, such factors as early screening, surveillance and early and adequate therapy can help to increase their life expectancy. The study was approved by the Independent Ethics Committee and the Scientific Council of the Almazov National Medical Research Centre of Ministry of Healthcare of the Russian Federation.

Despite remarkable progress in the management of pediatric oncological diseases they remain one of the leading causes of mortality. The disease progression due to tumor resistance, treatment-induced toxic effects and infections complications may contribute to the lethality. New diagnostic technologies facilitate the identification of clinically significant genetic alterations for individualization of therapy approach in order to increase its effectiveness, reduce associated toxicity and improve quality of life of patients and their families. The most promising diagnostic approach is based on next-generation sequencing and includes targeted-, whole exome- and genome sequencing of patients’ blood DNA and tumor tissue. Despite the low rate of detected pathogenic alterations, some of them have prognostic significance, determine sensitivity to anticancer agents and targeted therapy. Moreover, targeted therapy in some cancer types shows benefit over standard therapeutic options. The application of targeted therapy in pediatric patients poses more challenges than in adults. This is due to the absence of established doses, regimens and indications for targeted agents in pediatric clinical trials, risks of associated toxicity and its high cost. This paper summarizes the data on molecular genetic markers, which are potentially helpful in guiding therapy for cancer in children.

Background. Early identification of pediatric central nervous system (CNS) tumors is important in relation to disease prognosis, as well as long-term treatment outcomes, which determine subsequent quality of life. The predominance of embryonal tumors (ETs) in early childhood actualizes the problem of timely verification of the diagnosis. Factors contributing to the extension of diagnostic time in the presented patient’s cohort include the inability to adequately verbalize complaints in young children, a wide range of clinical presentations, including nonspecific ones, the relatively low incidence of ET in the population and the low level of oncological alertness among specialists. This determines the need for a more careful assessment of the clinical manifestations and disease-associated symptoms by doctors of all specialties and, especially, primary care specialists. Aim. Analysis of clinical symptoms at the disease’s onset in pediatric CNS ET in order to determine their associations with the tumor’s characteristics (site, hystologic type) and the patient’s features. Materials and methods. A retrospective analysis of data from 124 pediatric patients with CNS ET who received treatment from 2010 to 2023 in the departments of pediatric oncology of the Almazov National Medical Research Center and the St. Petersburg Scientific Research Center for Medical Sciences (o) named after. N. P. Napalkov. The analyzed parameters were the age of manifestation, initial symptoms, duration of the anamnesis and the period before verification of the diagnosis, localization and histological type of tumors. For statistical analysis, Fisher’s exact test, modified Pearson test, Kruskal-Wallis and Mann-Whitney tests, as well as (to assess the duration of anamnesis) the Cox model were used. Results. The most common type of CNS ET in the study group was medulloblastoma (MB; 66.1%). The average age of patients, in general, was 61 months, boys predominated (58%). The median age varied depending on the histological tumor type: the maximum was 72 months in patients with medulloblastoma and the minimum was 9 months in children with atypical teratoid rhabdoid tumor (ATRT). Both medians are significantly different from the total median (29 months) of all other tumors (p = 6.53 ∙ 10-4 and p = 0.029, respectively). The most frequent symptoms in patients with ET were nausea and vomiting (68%), headache (50%), and gait disturbances (25.6%). Increased head circumference/bulging fontanel (p = 0.0016) and torticollis (p = 0.0057) were the most common symptoms associated with younger age. Headache (p = 1.30 ∙ 10-9), nausea and vomiting (p = 0.019), diplopia (p = 0.0057), weight loss (p = 0.017) and dizziness (p = 0.013) were associated with older age. Headache was predominated symptom in medulloblastoma (p = 2.60 ∙ 10-4) compared to other ETs, and less common in ATRT (p = 1.51 ∙ 10-4), which may be due to the patient’s age. Fontanel bulging in medulloblastoma, unlike other ET, was not observed, which is also associated with age. Seizures were observed in all cases of CNS neuroblastoma - significantly more often (p = 0.034) than in other ETs. The most common tumor location was the posterior cranial fossa (PCF) (83.6%). PCF localization was associated with headache (p = 0.05, borderline significance) and nausea/vomiting (p = 0.040). Parietal localization was associated with seizures (p = 0.041). Four patients in the cohort had asymptomatic disease’s manifestations. The diagnosis was established by a routine screening examination. The absence of symptoms was associated with location outside the PCF (p = 0.011) and with younger age (p = 0.053, borderline significance). The diagnosis was established in a significantly shorter time if children had symptoms such as nausea and vomiting (p=0.0017), paresis and paralysis (p=0.0059). Conclusion. In patients with CNS ETs, statistically significant relationships are revealed between age, histological type, tumor site and certain symptoms. Nevertheless, the absence of strictly specific clinical manifestation determines the indications for a careful assessment of the pediatric somatic and neurological status and timely neuroimaging in children when even potential symptoms typical for CNS tumors are identified.

Metronomic chemotherapy (MCT) is a promising direction of anticancer therapy, as well as in pediatric oncology, and its administration in patients with refractory and recurrent tumors of the central nervous system becomes increasingly relevant. Being a regimen of low doses of antitumor agents with different mechanisms of action in a continuous mode for a long time, it allows to overcome the resistance of tumor cells and to minimize the toxic effects of treatment. Today, the issues of rational choice of MCT regimens, which are dependent on the type of tumor, and the application of biomarkers of its effectiveness, remain controversial. The article discusses in detail the biological effects of MCT with an accent on antiangiogenic one, as well as the possibilities and limitations of MCT application in pediatric practice and the results of studies in tumors of the central nervous system.

BACKGROUND:Methylation analysis has become a powerful diagnostic tool in modern neurooncology. This technique is valuable to diagnose new brain tumor types.OBJECTIVE:To describe the MRI and histological pattern of neuroepithelial tumor with PLAGL1 gene fusion.MATERIAL AND METHODS:We present a 6-year-old patient with small right frontal intraaxial tumor causing drug resistant epilepsy. Despite indolent preoperative clinical course and MRI features suggesting glioneuronal tumor, histological evaluation revealed characteristics of high-grade glioma, ependymoma and neuroblastoma.RESULTS:Methylation analysis of tumor DNA confirmed a new type of a recently discovered neoplasm - neuroepithelial tumor with PLAGL1 fusion (NET PLAGL1). PCR confirmed fusion of PLAGL1 and EWSR1 genes. No seizures were observed throughout the follow-up period. There was no tumor relapse a year after surgery.CONCLUSION:Methylation analysis in neurooncology is essential for unclear tumor morphology or divergence between histological and clinical data. In our case, this technique confirmed benign nature of tumor, and we preferred follow-up without unnecessary adjuvant treatment.

Diagnostic and treatment facilities in pediatric oncology have reached a very technological advances in a short period of time, contributing to increased relapse-free and overall survival rates. Obviously, the key factors are the improvement of diagnostic and screening programs, anticancer and concomitant therapy, including personification of clinical guidelines for monitoring and correction of early and late complications in time. Issues regarding the quality of life of patients, including social, psychological rehabilitation and aspects of reproductive potential, are becoming highly actual. The critical importance is that an informed multidisciplinary team of specialists at all stages of anticancer treatment should be involved. This article presents the main algorithms and the most significant issues for pediatricians in the diagnosis and supervision of patients with an oncological diagnosis, using the example of medulloblastoma, as the most common malignant tumor of the central nervous system in children. The proposed recommendations are based on a retrospective analysis of pediatric patients with relapsed and refractory forms of medulloblastoma (n = 270) who received antitumor therapy in the period from 07/01/1993 to 07/01/2023, as well as international clinical data.

Introduction. Atypical teratoid/rhabdoid tumor (ATRT) of the central nervous system (CNS) belongs to the embryonic group, occurs mainly in children under 3 years of age and is characterized by an extremely aggressive clinical course and unfavorable outcome. However, there is not enough data about the heterogeneity of the clinical course of CNS ATRT and the role of clinical and therapeutic prognostic factors in patients under 1 year of age and 1–3 years of age. The aim of this study was to conduct a comparative evaluation of treatment results in children with CNS ATRT in the indicated age groups. Materials and methods. From 2008 till 2021 years 106 patients were included in this study. Each patient underwent a therapeutic program according to determined protocol (ATRT-2006, MUV-ATRT, EU-RHAB and individual variant). All patients were divided into 2 groups according to age: from 1 to 12 months – 41 patients, from 13 to 36 months – 65. Median of the age was 16 (9–23) months. These cohorts of patients (1–12 months and 13–36 months) were comparable in clinical and therapeutic characteristics depending on gender, localization of the primary tumor site, stage of the disease, extent of surgical resection, therapeutic protocol, number of patients, who underwent radiation therapy (RT), high-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT), intrathecal/ intraventricular chemotherapy. Results. At the time of analysis 48 (45.3 %) patients were alive, 58 (54.7 %) patients died, of whom 52 (90 %) from disease progression and 6 (10 %) from therapeutic complications. One-year progression-free survival (PFS) in the group from 1 to 12 months was 32 %, 2-year – 18 %, 5-year – 18 %; one-year overall survival (OS) – 53 %, 2-year – 29 %, 5-year – 25 % with a median follow-up 8 and 13 months respectively. One-year PFS in the group from 13 to 36 months was 61 %, 2-year – 36 %, 5-year – 33 %; one-year OS – 86 %, 2-year – 67 %, 5-year – 49 % with a median follow-up 19 and 38 months respectively. In our study we identified the main predictors of the PFS and OS improvement in patients with ATRT CNS of each age group. In the 1–12 month group, these factors were: absence of metastatic involvement, MUV-ATRT therapeutic protocol, RT and HDCT with auto-HSCT; in the 13–36 months group: gross total/near gross total resection of the primary tumor cite, ATRT-2006 therapeutic protocol and RT. Conclusion. Despite the fact, that the presence of a diagnosis of ATRT CNS in children under 3 years of age is usually associated with a high risk of disease progression and recurrence, the results of our study demonstrate the heterogeneity of the clinical and therapeutic profile in this age group of patients.

Using the example of a recurrent tumor with a 10-year follow-up, the authors show that mutation of the IDH1/2 genes in astrocytomas is not always an early event in the pathogenesis of glioma, that in rare cases a 1p19q codeletion can be found in astrocytomas, and that IDH-mutant tumors can occur in childhood.

Medulloblastomas of the WNT molecular group (MB-WNT) represent the smallest group of MB and account for only 10 % of the total. This molecular group is characterized by a favorable prognosis. Given the aggressive treatment regimens for MB, reducing the intensity of therapy for prognostically favorable tumors seems justified. Purpose of the study – to demonstrate the results of treatment of children with MB-WNT and to determine the impact on survival of various prognostic factors. The study included 85 patients with MB-WNT under the age of 18 who received treatment and were followed up from 1993 to 2022. Median age at diagnosis was 10 years (min – 3, max – 17). All patients had classical MB. Metastatic spread of the tumor at the time of diagnosis was detected in 18 (21.2 %) patients, the presence of a residual tumor according to postoperative magnetic resonance imaging – in 32 (37.7 %). Somatic mutations in the TP53 gene were detected in 10 (7.1 %) patients, in the CTNNB1 gene – in 79 (92.9 %), in the APC gene – in 5 (5.9 %), chromosome 6 monosomy – in 76 (89.4 %) children. At the time of the analysis, 74 (87.1 %) patients were alive, 11 (12.9 %) patients died, a relapse was diagnosed in 6 (7.1 %) patients, of which 5 died from disease progression, 1 patient is alive in the second remission. One patient in long-term remission developed secondary meningioma 20 years after the diagnosis of MB. The 10-year progression-free survival (PFS) was 0.92. 5-year overall survival (OS) was 0.90, 10-year – 0.86. The median OS is 112 months. When analyzing the sample of patients with MB-WNT in our study, PFS and OS were statistically significantly higher in girls without metastatic tumor spread, with total resection of the tumor, stratified into the low-risk group, and in the absence of a somatic mutation in the TP53 gene in the tumor tissue. In multivariate analysis, PFS was influenced by the stage of the disease and the presence of a somatic mutation in the TP53 gene in the tumor tissue; on OS – only the presence of a somatic mutation in the TP53 gene in the tumor tissue.

Glioblastomas are malignant tumors that belong to the central nervous system and are challenging to diagnose due to their significant intratumoral heterogeneity, which makes molecular testing and diagnosis confirmation particularly difficult. In addition to identifying typical genetic mutations such as IDH, H3F3A G34 and K27, WHO recommendations emphasize the importance of analyzing the tumor epigenome to define its class based on DNA methylation patterns and methylation status of specific genomic regions, particularly the MGMT promoter region. Based on our clinical experience, molecular genetic studies sometimes yield contradictory results due to the heterogeneous cellular composition of glioblastomas. In this study, we present a series of observations made on 35 glioblastoma samples in which we compare the morphological features and the results of cell type detection by deconvolution method based on total DNA methylation profiles. Our results suggest that samples of mesenchymal class glioblastomas may contain over 50 % non-tumor immune cells, which should be considered in genetic testing of these tumors.

Currently, the daily routine of a molecular pathologist is DNA methylation and RNA and DNA sequencing. The authors, from the standpoint of researchers and clinicians, explain the molecular methods used not only to diagnose brain tumors, but also to search for possible targets for therapy.

Medulloblastoma (MB) is the most common malignant tumor of the central nervous system in pediatric patients. Despite the complex anticancer therapy approach, refractory and relapsing forms of the disease remain fatal in most cases and account for approximately 30%. To date, repeated surgery, radiation, and chemotherapy can be used as life-prolonging treatment options; nevertheless, it should be emphasized that there are no standardized approaches based on existing data of molecular variants of MB. It is obvious that only a deep understanding of the biological mechanisms in association with clinical aspects in refractory and relapsing forms of MB would make it possible to personalize second- and subsequent-line therapy in order to achieve maximum efficiency and minimize early and long-term toxicity. The article presents the current understanding of prognostic factors in relapsed/refractory forms of MB, methods of modern diagnostics, as well as existing and perspective treatment options based on the biological and clinical aspects of the disease.

BACKGROUND:Differential diagnosis of supratentorial ependymomas is of particular difficulty in neurooncology due to nonspecific clinical and radiographic findings, a rare seen «classic» morphological picture, and a nonspecific immunophenotype. Thanks to molecular genetic methods, in particular real-time PCR, it has become possible to verify supratentorial ependymomas and identify their molecular group, on which further prognosis depends.OBJECTIVE:To develop a set of molecular genetic tests based on real-time PCR to verify supratentorial ependymomas.MATERIAL AND METHODS:56 tissue samples were collected from patients with supratentorial ependymomas, WHO Grade II, and anaplastic ependymomas, WHO Grade III. We developed primers and fluorescent TaqMan probes for real-time PCR analysis to detect the ZFTA::RELA, ZFTA::MAML2, ZFTA::NCOA2, ZFTA::MAML3, YAP1::MAMLD1, and YAP1::FAM118B gene fusions. For immunohistochemical analysis, monoclonal rabbit anti-NF-kb p65 antibodies (HUABIO, China) were used, the study was carried out on AutostainerLink 48 immunostainer (DAKO, Denmark).RESULTS:Real-time PCR was able to verify the diagnosis for 69.9% (n=39) of samples and classify them into molecular groups of ZFTA- or YAP1-positive supratentorial ependymomas. Immunohistochemically it was possible to verify 58% (n=29) ependymomas.CONCLUSION:Diagnosis by real-time PCR is a relatively fast, accessible and easily interpreted method that allows verification of the molecular group in 70% of cases of supratentorial ependymomas without the use of additional methods.

BACKGROUND: Disorders of carbohydrate metabolism are frequent complications after complex treatment of cancer. Early detection of these disorders allows to modify lifestyle, if necessary, apply drug therapy and correct the identified changes in time, which will subsequently lead to a decrease in cardiovascular risks, an improvement in the quality and an increase in the life expectancy of this group of patients.AIM: To identify the frequency of occurrence and determine the optimal methods for early diagnosis of carbohydrate metabolism disorders in children after complex treatment of medulloblastoma.MATERIALS AND METHODS: 97 patients (64 boys) were examined after complex treatment of medulloblastoma (surgical treatment, craniospinal radiation therapy [CSI], chemotherapy). The median age at the time of the survey was 11.2 (5.29 -17.9) years. The average follow-up period after the end of all types of treatment is 4.7 (0.59 - 11.94) years. At the time of examination, all patients were compensated for hypothyroidism and hypocorticism (if any), and no one was on growth hormone therapy. All patients underwent a standard oral glucose tolerance test (OGTT) and determination of the level of glycated hemoglobin (HbA1c).RESULTS: None of the patients had a basal glycemic level higher than 5.5 mmol / L. Impaired glucose tolerance ( glycemia at the 120th minute ≥7.8 mmol / L <11.09 mmol / L) was detected in 10 out of 97 patients (10.3%). 7 patients with IGT had insulin resistance (according to MATSUDA index), while 1 of them had normal HOMA-IR index. Only one patient with IGT had an increase in the level of glycated hemoglobin up to 6.2%. Insulin resistance (using the MATSUDA index) was present in 30 patients, and 11 of them had a normal HOMA-IR index. Thus, 34 out of 97 patients (35.1%) had disorders of carbohydrate metabolism (IGT and / or insulin resistance). At the same time, the level of glycated hemoglobin reflected disturbances in only one case, and the basal level of glycemia was not informative in any case.CONCLUSION: Assessment of basal levels of glycemia and insulin, as well as glycated hemoglobin, is insufficient to exclude disorders of carbohydrate metabolism in patients after complex treatment of medulloblastoma. It is advisable to carry out a standard OGTT.

Identification of specific alterations in tumors (as a rule, these are mutations or gene fusions) makes it possible to prescribe targeted drugs of the second line of therapy or, in some cases of inoperable tumors, to observe not only a gradual partial response of the tumor to treatment, but also the removal of these patients from the category of incurable ones. The article describes a new rare type of BRAF::EPB41L2 gene fusion detected in a piloid astrocytoma that developed in the posterior cranial fossa in an 11-year-old boy.

Thanks to modern treatment protocols, childhood cancer survivors (CCS) are a very fast-growing population nowadays. Cancer therapy inevitably leads to different late adverse effects, where endocrine disorders are highly prevalent, including growth hormone deficiency (GHD) which is the most common endocrine outcome after cancer treatment in childhood and contributes to impaired growth. Short stature is a big issue, which leads to problems in psychological and social adaptation of patients and reduces their quality of life. Impact of GH treatment on various physiological processes and global outcome of CCS is of great interest. Several studies have demonstrated an influence of GH and IGF-1 on the development/tumour growth, cell proliferation. In this regard, the issue of increasing the risk of cancer recurrence and/or the development of secondary neoplasms in CCS, causes a lot of controversy and is the subject of continuous evaluation. In this review, we went through the available data on the prevalence and pathogenesis of GHD following chemo- and radiotherapy, in particular after treatment of brain tumors and acute lymphoblastic leukaemia in childhood. In addition, here we discuss the existing problems in the diagnosis of GHD, the safety of GH replacement therapy, as well as the treatment algorithm of the GHD in adults.