Late effects of childhood cancer treatment in long-term survivors diagnosed before the age of 3 years - A multicenter, nationwide study.

BACKGROUND: The effect of age on the incidence of late sequelae that occur after anticancer treatment in childhood is still not fully elucidated. In this multicenter study of long-term survivors diagnosed before age of three, we investigated the prevalence of late effects many years after treatment. METHODS: The study group (n = 561) was selected from the Polish National Childhood Cancer Survivors Registry (n = 1761) created in 2007. A survivor was defined as an individual who has survived at least 5 years after completion of anticancer treatment. All children were diagnosed between 1991 and 2016, mean age at diagnosis was 1.82 years (range 0.03-2.99) and median follow up time - 9.85 years (range 5.0-23.6). They were treated in accordance with international protocols approved by the Polish Pediatric Leukemia and Lymphoma Group and Polish Solid Tumor Group. Chemotherapy alone was used in 192 (34.2%), chemotherapy and radiotherapy - 56 (10%), chemotherapy and surgery - 176 (31.4%), chemotherapy, radiotherapy, and surgery - 79 (14.1%), and surgery alone in 58 patients (10.3%). RESULTS: Of all patients enrolled to the study, only 94 (16.8%) had normal function of all organs. Seventy-six (13.5%) children developed dysfunction in one organ, another 83 (14.8%) had symptoms or complaints suggestive of dysfunction in two organs or systems, 88 (15.7%) had abnormalities in three organs, and 220 (39.2%) had at least four or more dysfunctions. In the entire study group, dysfunctions most frequently (> 20% of cases) involved the following organs/systems: circulatory - 21.8%, urinary - 30.8%, gastrointestinal - 20.8%, immune - 23.5%, vision - 20.7%, hearing - 21.8%, and oral and masticatory dysfunction - 26.9%. We did not find any significant differences in organ dysfunction between children diagnosed under the age of 1 and those diagnosed at the age of 1-3, except for a lower incidence of thyroid abnormalities (p = 0.007) and the higher prevalence of liver dysfunction in youngest patients. In the subset with longer follow-up period (> 10 years) more frequent thyroid abnormalities (p = 0.019), male (p = 0.002) and female (p = 0.026) gonads dysfunction, as well as musculoskeletal problems (p < 0.001) were observed. Among subjects who received radiotherapy compared to those who did not, short stature (p = 0.001), and dysfunction of the following systems/organs - circulatory (p = 0.049), urinary (p = 0.012), thyroid gland (p < 0.0001), nervous (p = 0.007), immunological (p = 0.002), liver (p = 0.03), dental or chewing difficulties (p = 0.001), hearing (p = 0.001) and musculoskeletal (p = 0.026) were more frequently reported. When multimodal therapy was applied (chemotherapy, radiotherapy, and surgery) a higher incidence of short stature (p = 0.007), urinary system disorders (p < 0.0001), thyroid dysfunction (p < 0.0001), hearing loss (p < 0.0001), and skin problems (p = 0.031) were observed. CONCLUSION: This study confirms that radiotherapy and some specific toxicity of cytostatics are the most important factors affecting organ function. Apart from a higher incidence of liver dysfunction in the youngest patients, there were no significant differences in organ and system toxicities between children diagnosed under the age of 1 and those diagnosed at the age of 1-3. We have shown that this group requires systematic, careful and long-term follow-up.

Molecular Genetics Diversity of Primary Hemophagocytic Lymphohistiocytosis among Polish Pediatric Patients.

Hemophagocytic lymphohistiocytosis (HLH) is a clinical syndrome of life-threatening inflammation caused by an excessive, prolonged and ineffective immune response. An increasing number of HLH cases is recognized in Poland, but the genetic causes of familial HLH (FHL) have not been reported. We investigated the molecular genetics and associated outcomes of pediatric patients who met HLH criteria. We studied 54 patients with HLH, 36 of whom received genetic studies. Twenty-five patients were subjected to direct sequencing of the PRF1, UNC13D, STX11, XIAP and SH2D1A genes. Additionally, 11 patients were subjected to targeted next-generation sequencing. In our study group, 17 patients (31%) were diagnosed with primary HLH, with bi-allelic FHL variants identified in 13 (36%) patients whereas hemizygous changes were identified in 4 patients with X-linked lymphoproliferative diseases. In addition, one patient was diagnosed with X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection and neoplasia due to a hemizygous MAGT1 variant; another newborn was diagnosed with auto-inflammatory syndrome caused by MVK variants. The majority (65%) of FHL patients carried UNC13D pathogenic variants, whereas PRF1 variants occurred in two patients. Novel variants in UNC13D, PRF1 and XIAP were detected. Epstein-Barr virus was the most common trigger noted in 23 (65%) of the patients with secondary HLH. In three patients with secondary HLH, heterozygous variants of FHL genes were found. Overall survival for the entire study group was 74% with a median of 3.6 years of follow-up. Our results highlight the diversity of molecular causes of primary HLH in Poland.

Disturbances in NK Cells in Various Types of Hemophagocytic Lymphohistiocytosis in a Population of Polish Children.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease associated with immune system hyperactivation and the appearance of serious systemic disturbances. The purpose of this study was an assessment of natural killer (NK) cell disturbances in a group of children with clinical signs of HLH. A total of 43 children with HLH and 17 healthy children were enrolled in the study. NK phenotyping, intracellular perforin staining, and cytotoxicity tests were performed by using the flow cytometry method. HLH patients were divided into 6 HLH types: 9% infection-related HLH; 7% malignancy-related HLH; 21% macrophage activating syndrome; 12% familial hemophagocytic lymphohistiocytosis; 2% X-linked lymphoproliferative syndrome; and 49% as HLH of unknown background. A positive correlation was observed between cytotoxicity and NK cells in children with HLH (P=0.01). In all HLH groups, the percentage of NK cells was significantly lower than in the control population. The spontaneous cytotoxicity was significantly lower in HLH patients. The results presented in this study indicate the importance of impaired function and the number of NK cells in the pathogenesis of HLH. Nonetheless, the background of disturbances seems to be different in various cases.