Relevance. In 2021, 2998 children (0–14 years old) with a diagnosis of malignant tumors were registered in Russia as a whole and 290 in the Northwestern Federal District of the Russian Federation. The incidence rates of children in Russia and in the North-Western Federal District of Russia are close – 11.6 and 12.7 per 100 000, which allows to expand our calculations of child survival according to the database of the Population cancer registry (DB PCR) of the Northwestern Federal District. The Northwestern Federal District of the Russian Federation is the only federal district in Russia where a PCR has been created that works in accordance with international standards and calculates observed and relative survival rates.

Until now, since 1994, we have had the opportunity to calculate the survival rates of patients with malignant tumors only in St. Petersburg on the basis of the DB created by the first PCR in Russia, operating according to international standards.

In February 2019, a unified DB of the PCR of the Northwestern Federal District of the Russian Federation was formed, which significantly expanded the possibility of studying the patterns of prevalence and effectiveness of treatment of patients with malignant tumors, including rare localization of malignant tumors, which include the child population (0–17 years old), especially when we are trying to investigate a detailed localization and histological structure of tumors separately for children (0–14 years) and adolescents (15–17 years).

The purpose of the study is to study the effectiveness of anti-cancer measures carried out in the country by calculating objective indicators according to international standards – the one- and 5-year survival rate of children (0–14 years old) with malignant tumors for all tumors and for individual localizations.

Materials and methods. The material of the study was a DB of patients with malignant tumors of the Northwestern Federal District of the Russian Federation with a volume of more than 1 million 450 thousand observations, including a childrenʼs contingent – more than 5,000 observations collected from 1995 to 2021. The Northwestern Federal District of the Russian Federation has a population of 13.9 million people, which is more than the population of Belarus, Latvia and Estonia combined. The number of children is more than 2.5 million. Survival rate of adolescents (15–17 years) our next article is dedicated to. Standard methods of calculating indicators recommended by the International Association of Cancer Registries for Epidemiological Studies (Eurocare program) were used.

Results. The study showed an increase in the one-year survival rate of sick children (0–14 years) from 82.4 to 89.0 % from 2000 to 2018, or by 8.0 %, 5-year from 66.7 to 70.5 % from 2000 to 2017, or by 5.7 %, with a higher level for girls. In national centers, the results of treatment of children with malignant tumors are even higher; however, accessibility to modern methods of treatment of children of all administrative territories is important to us.

Conclusions. For the first time in Russia, the effectiveness of anti-cancer measures in organizing oncological care for children at the federal district level has been demonstrated for more than 10 localizations of malignant tumors over a long observation period.

Relevance. The number of uveal melanomas (UM) in the structure of melanomas of the visual organ and its adnexa is approximately 85 %. This malignant intraocular neoplasm affects mainly the adult population. UM is a rather rare phenomenon among children and, according to various authors, accounts for only 0.5–1.3 % of all UM. The relevance of studying the topic of UM in children and adolescents lies in studying the issue of treatment with an organ-preserving purpose, since this aspect has medical and social significance.

Purpose of the study – to analyze clinical and histological features, course of disease and treatment approaches in the children and adolescents under 20 years.

Materials and methods. The study includes 29 patients with UM, treated and observed from 1992 to 2023. Median patients’ age at the time of treatment was 17 years (from 10 to 20 years old). 45 % patients were male, 55 % – female. The analyzed data included age at the time of treatment, gender, affected eye, tumor’s localization, size and other characteristics (optic nerve and ciliary body (CB) involvement, extraocular spread) and the treatment method.

Results. Mostly, UM had choroidal localization (n = 17, 59 %), fewer UM had panuveal localization (n = 5, 17 %); iris and CB melanoma took place in 14 % (n = 4), CB and choroidal melanoma – in 7 % (n = 2) and in only 1 (3 %) case we observed iris melanoma. TNM (AJCC) classification of our patients with UM was the following: T1 – 5 (17 %) eyes; T2 – 8 (28 %); T3 – 13 (45 %); T4 – 3 (10 %).

Organ-preserving methods of treatment were preferable (n = 20, 69 %). Enucleation was performed in 9 (31 %) cases. Organ-preserving treatment included surgical treatment (n = 9), brachytherapy (BT) (n = 6), BT with transpupillary thermotherapy (TTT) (n = 1), TTT (n = 3) and Gamma Knife stereotactic radiosurgery (n = 1). After organ-preserving treatment we confronted complications in 10 (34 %) cases: macular edema (n = 4), posterior subcapsular cataract (n = 3), neuropathy (n = 2) and phtisis bulbi (n = 1).

According to histopathological examination 50 % of eyes (after surgical treatment and enucleation) had spindle cell type of UM and only 7 % had epithelioid cell type. 6 patients (43 %) had mixed cell type of UM. The mean follow-up was 68 months (from 6 mo. to 21 year). No patients died during follow-up. One (1 %) patient developed liver metastasis. Disease-free survival at 3 and 5 years of follow-up was 94 %.

Conclusion. UM in children and adolescents possesses differences compared to UM in adults. Survival prognosis of UM in children and adolescents is better than in adults. However, true reasons of this feature require further research.

Relevance. Radiation therapy (RT) is one of the components of multimodal treatment among patients with high-risk neuroblastoma (NB), and in combination with surgical treatment is a mandatory element of local control of the primary tumor. At the same time, RT for metastatic sites persisting after completion of induction therapy is not a standard protocol treatment in primary patients with high-risk NB. The effect of RT on metastatic sites on improving long-term survival and reducing recurrence rates continues to be studied.

Aim to the study – to investigate approaches to RT for single metastatic foci persisting after induction therapy among patients with NB highrisk group as part of the consolidation phase of first-line therapy.

Materials and methods. The retrospective analysis included 11 patients with high-risk NB who underwent RT for metastatic foci as part of first-line therapy at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Health of Russia from 01.2012 to 12.2023. Patients received therapy according to the modified protocol GPON-NB2004. The indication for RT was the persistence of a single metastatic site detected by 123I-metaiodobenzylguanidine scintigraphy or computed tomography/magnetic resonance imaging after completion of induction chemotherapy.

Results. The median age was 31.9 months (range 9.4–128.6 months). All patients were initially with stage 4 disease (one patient had metastatic focus in the orbit without detection of the primary tumor). MYCN gene amplification was detected in 4/11 (36 %) cases. 10/11 (91 %) patients achieved а partial response after induction therapy. In all cases, only one metastatic focus was irradiated. 2/11 patients received radiation to both the primary tumor and metastatic focus.

10/11 patients received RT to metastatic sites localized in skeletal bones, 1/11 – to a distant lymph node. Seven of 11 sites received 21 Gy in 14 fractions. The median follow-up was 40 months (range 13–97 months). Only 1 of 11 patients receiving metastatic site irradiation experienced relapse in an irradiated distant site 24 months later. The 3-year relapse-free survival and overall survival were 54 % and 80 % respectively.

Conclusions. RT may be an effective method of local control in oligometastatic disease and in case of persisted single metastatic foci after induction chemotherapy in the treatment of high-risk NB. Additional large studies are needed to confirm the role of RT in improving survival with irradiation of metastatic sites.

Relevance. Modern advances in risk-adapted chemotherapy allow achieving long-term overall survival in 97.7 % of children with classical Hodgkin lymphoma (cHL), even at widespread stages of the disease. However, relapses and refractory course of cHL are noted in 10 % of cases. In this regard, the search for additional prognostic factors for the course of HL continues.

The aim of the study – to evaluate the significance of using the leukocyte ratio index to assess the effectiveness of antitumor treatment in pubertal children with cHL.

Materials and methods. The study included children of both genders (22 boys and 18 girls) with a morphoimmunohistochemically confirmed diagnosis of cHL. Before treatment and after each course of chemotherapy, the general blood test parameters were determined with subsequent calculation of the leukocyte ratio using the formula: the absolute number of neutrophils was divided by the absolute number of lymphocytes. The results of the study of the leukocyte ratio of 40 conditionally healthy pubertal children in equal sex numbers were used as normal indicators. Statistical processing of the results was performed using the STATISTICA 10.0 program.

Results. In all children with cHL, the leukocyte ratio values exceeded the values of conditionally healthy children from 2.4 to 4.4 times, while there was an increase in the leukocyte ratio by 1.7 times in children with advanced (III, IV) stages of the tumor process compared to stage II. Retrospective analysis of the leukocyte ratio values in children of both genders with HL with remission achieved due to the first line of therapy before treatment demonstrated an increase in the leukocyte ratio by 3.5 times in boys and 4.1 times in girls. At all stages of treatment from the 1^st to the 6^th course, a statistically significant decrease in the studied indicator was revealed compared to the value of the indicator before treatment in boys by an average of 3.6 times, and in girls by an average of 4.3 times. The indicator was within the reference values of the norm. Retrospective analysis of the leukocyte ratio values in adolescent children with refractory and progressive cHL (4 boys and 3 girls) revealed that before treatment, compared to the norm, the average value was 2.6 times higher in boys and 4.2 times higher in girls. Compared with the initial values of the leukocyte ratio in adolescent children with cHL and remission achieved due to the first line of therapy, the data obtained are statistically insignificant. Having analyzed the leukocyte ratio values after each course of polychemotherapy for each patient in particular, it turned out that the indicator statistically significantly increased after those courses in which refractory course or progression of the disease was detected clinically and diagnostically (ultrasound examination, CT, PET/CT). The leukocyte ratio indicator responded by changing the value depending on the effect of subsequent lines of therapy.

Conclusions. In addition to objective instrumental and laboratory methods for assessing the effectiveness of specialized therapy (PET/CT with ¹⁸F-fluorodeoxyglucose, biopsy of the residual neoplasm), as an additional method for assessing the effectiveness of antitumor therapy in pubertal children with cHL, it is also possible to use the leukocyte ratio index based on the results of a complete blood count, which allows indirectly judging the effectiveness of the therapy and timely detection of refractory course or progression of cHL.

Primary malignant lung tumors are an extremely rare pathology in childhood and adolescents.

The purpose of this publication – is to review the most complete and significant retrospective studies on this pathology, to explore the epidemiology, clinical symptoms and treatment methods, as well as to assess the prognosis of the disease depending on the histological type of tumor.

Endothelial dysfunction (ED) is a key factor in the development of thrombotic complications and cardiovascular diseases. The article examines the biochemical and molecular mechanisms of ED. Special attention is given to the role of ED in the development of thrombosis in patients after splenectomy. In children, ED can be caused by congenital pathologies, chronic diseases, or surgical interventions, making this issue particularly relevant in pediatrics. Modern diagnostic methods are described, along with their limitations in pediatric practice. Potential therapeutic approaches are discussed, although standardized treatment protocols are lacking. The article emphasizes the importance of studying ED as a significant risk factor that requires new approaches in pediatrics and pediatric hematology.

Germ cell tumors (GCTs) are a heterogeneous group of tumors that develop from pluripotent germ cells, diagnosed most often in infants, young children, adolescents and young adults, and are characterized by different localization, histological picture, clinical course and prognosis. Despite the fairly high efficiency of modern standard chemotherapy protocols for GCTs, the treatment of their relapses and refractory forms, which make up to 30–40 % of all GCTs and have an extremely unfavorable prognosis, is very difficult. Currently, there is no single strategy for the treatment of relapses and refractory forms of GCTs, however, the world and domestic literature presents data on the successful use of high-dose chemotherapy (HDCT) in such patients followed by autologous hematopoietic stem cell transplantation (auto-HSCT). To develop and optimize protocols for this therapy method, and therefore improve the treatment outcomes for patients with relapses and refractory forms of GCT, it is necessary to analyze a larger number of studies from various transplant centers working in this area. The article presents current literature data on the use of HDCT followed by auto-HSCT in patients with GCT, as well as a clinical case of successful 2 courses of HDCT with auto-HSCT in tandem mode in a child with a refractory form of GCT with subsequent maintenance of complete remission for 2 years.

We present a clinical case of an extremely rare congenital brain tumor in a 6-month-old child – pineal anlage tumor (PAT), which occurs in 0.04 % of all brain neoplasms in childhood. Foreign literature describes 20 cases of PAT in children, while there are no such publications in the domestic literature.

At present, this tumor is not yet defined as a separate type in the latest edition of the WHO classification in 2021. In the WHO classification of 2007, PAT is described as a rare variant of pineoblastoma with melanotic, cartilaginous and/or rhabdomyoblast differentiation, characterized by heterogeneous elements of neuroepithelial and ectomesenchymal tissue, but without endodermal structures. Due to the rarity of this type of neoplasm, histologic diagnosis can be difficult for the morphologist.

Specific therapy has not been developed at present, the optimal treatment is the maximal complete surgical removal of the volumetric neoplasm, as well as polychemotherapy according to the protocol of pineoblastoma treatment. However, the efficacy of this strategy remains unclear.

The guidelines for the prevention and management of adverse events in patients receiving dinutuximab beta therapy provide recommendations for assessing the risk of development, prevention and management of adverse events.