Background: Globally, gastric cancer accounts for 1,089,000 new cases and 769,000 deaths annually, ranking fifth in overall cancer incidence and third in cancer-related mortality. The aim to determine HER2 expression in patients with gastric cancer and to evaluate its correlation with clinical and immunological biomarkers, as well as the need for further laboratory diagnostics. Aim: To determine HER2 expression in patients with gastric cancer and to evaluate its association with clinical and immunological biomarkers, as well as the potential need for further laboratory diagnostics. Materials and Methods: A retrospective study was conducted using archived materials from patients with gastric cancer at the Clinical Pathology, Molecular Genetics, and Pathology Laboratories of the National Cancer Center of Mongolia, covering the period from 2019 to June 2025. HER2 protein expression in tumor tissue was assessed using immunohistochemistry (IHC), and chromogenic in situ hybridization (CISH-HER2) was employed to confirm gene amplification. Statistical analysis was performed using the Prisma-10 software. Results: In our study, among 210 cases of gastric cancer evaluated by IHC for HER2, 46 (21.9%) were HER2-positive and 164 (78.1%) were HER2-negative. When comparing patients with gastric cancer stratified into HER2 1+ (negative) and HER2 3+ (positive) groups, no statistically significant differences (p < 0.05) were observed in age, sex, tumor location (surgically resected tissue), morphology, or disease stage. However, a higher proportion of males was noted in the HER2 3+ group (80.9%), though this did not reach statistical significance (p = 0.0879). Significant associations were found with tumor markers. Elevated serum CA-72-4 (>5 ng/mL) was more frequent in the HER2 3+ group (58.8%; p = 0.0069). In contrast, elevated CA-19-9 (>35 U/mL) was more common in the HER2 1+ group (93.5%; p = 0.0117), and elevated CEA (>6.9 U/mL) was also predominant in the HER2 1+ group (90.6%; p = 0.002). These findings suggest that HER2 3+ status predominates in cases with elevated CA-72-4, which may influence diagnostic strategies and HER2-targeted therapies (e.g., trastuzumab). Conversely, elevated CA-19-9 and CEA were more associated with HER2 1+ status, indicating a need for further detailed investigation of these markers in relation to HER2 expression. In patients evaluated by CISH for HER2 expression, stratification into HER2-positive and HER2-negative groups revealed no statistically significant differences (p < 0.05) in age, sex, tumor location, morphology, stage, or serum tumor markers (CA-72-4, CA-19-9, CEA). This suggests that HER2 status (positive/negative) may be independent of these variables. Although HER2 positivity was higher in poorly differentiated tumors (48% vs. 30.6% negative; p=0.1414) and in stage IV disease (50% vs. 39.3% negative; p=0.2607), these differences were not statistically significant. Elevated serum markers (CA-72-4, CA-19-9, CEA) were observed but showed no significant correlation with HER2 status. Conclusion Determining the molecular profile of gastric cancer patients can significantly contribute to refining clinical diagnosis, developing treatment strategies, enhancing therapeutic outcomes, and improving patients’ quality of life.

Clinical characteristics differences and risk factors of coronavirus disease and influenza in children 0-18 years Background: In worldwide, 176190 children infected with SARS-CoV-2 during April of 2020. According 01/09/2021, 46019 children had diagnosed with COVID-19 in Mongolia, were 19.5% of all cases. During COVID-19 infection, respiratory and digestive symptoms were commonly presented in children. Although the symptoms of coronavirus disease in children and adults are similar, in general, it was relatively mildly than adults, but from clinical observations reported that the infection occurs more severely in children and leads to death. During the coronavirus pandemic, it has been reported that children have Kawasaki syndrome, cardiac myopathy, coronary artery changes, and digestive system problems. Cardiac dysfunction in children may have recovered without sequelae, and further long-term follow-up studies are necessary. We aimed study clinical characteristics differences and risk factors of coronavirus disease and influenza in children 0-18 years. Materials and methods: The study was conducted Children hospital of NCMCH from October 01, 2021 to April 01, 2022, participated 594 inpatients with COVID-19 and influenza, and studied clinical characteristics, laboratory and functional diagnostic changes, treatment, and complications of the coronavirus disease and influenza. Results: The study included 450 children aged 0-18 years with confirmed COVID-19 infection and 144 children with influenza. In social-demographic indicators, the mean age of children is 4±4.8 years, and 58.6% are male. Children age group included 0-4 ages, 5-9 ages, 10-15 ages and over 15 ages (62.4%, 17.5%, 16.2%, and 3.7%), respectively. As for influenza, 39.7% were children aged 0-9. In 8 cases, they received the COVID-19 vaccine but became ill with COVID-19. As for the variants of COVID-19 infection, 231(41.8%) alpha, 219(48.0%) delta, and 144(24.2%) influenza according to the wave period and clinical differentiation. In severity of diseases, 2(0.4%) were mild, 312(69.3%) were moderate, 117(26.0%) were severe, and 17(3.8%) were critical severe. There is a statistically significant difference in the severity of the disease between COVID-19 and influenza. 1 death (0.4%) occurred in cases of COVID-19. The mean days of inpatients with COVID-19 was 12.4±5.5 and mean days of inpatients with influenza 8.6±3.64. When assess signs of children, fever, cough and food aversion were main signs among both group of alpha and delta varientin COVID-19. Specifically, 67.3% had fever, 63.3% cough, 16.4% runny nose, 8% chest pain, 10.2% headache, 15.5% fatigue, and 0.9% decreased sense of taste and smell. There is a statistically significant difference (p<0.000) in the symptoms of cough, chest pain, general toxication symptoms and decreased sense of taste and smell in the case of COVID-19 and influenza. During influenza, symptoms of chest tightness and respiratory distress were observed in 10 (7.4%) children during severe illness. 0.5% of all cases of COVID-19 with sinus arrhythmia, and atrioventricular block were detected 0.9% of all cases by electrocardiogram analysis. When studying the underlying medical conditions of children in relation to the complications of COVID-19 and influenza, children diagnosed with heart defects, malnutrition, weakness, anemia, cerebral palsy, and other chronic diseases have a greater impact on the severity of the disease of COVID-19 than those with influenza. In the study of the factors affecting the severity of the COVID-19 infection, the child's age and gender did not have an effect, while the presence of a heart defect in the child increased the risk of complications by 5 times (p<0.001). Conclusions: Among 0-4 aged children with COVID-19 are occurred more hospitalization, brightly presented symptoms in children with chronic diseases, are being more severe and hospitalization days are more than in children with influenza. Symptoms of fever, cough, and runny nose are more common in children during flu and influenza, while headache, abdominal pain, dehydration, and reduced sense of taste and smell are significantly more common in the case of COVID-19. On the other hand, symptoms of chest pain, weakness, and fatigue were found in the 2 groups. The comorbidities (congenital cardiac anomalies, malnutrition, weakness, anemia, cerebral palsy, and other chronic diseases) are being risk factors for the severity of coronavirus disease.

Early detection of bronchial asthma in children and establishment of a national continuous monitoring system Introduction: Bronchial asthma - a chronic inflammatory disease with recurrent allergic reactions characterized by increased sensitivity of the bronchi to various factors, swelling of the bronchial mucosa, excessive mucus secretion, and narrowing of the airways due to severe muscle contraction. Early detection of bronchial asthma in childhood, its prevalence, and the establishment of a continuous monitoring system to assess the effectiveness of follow-up treatment Materials and methods: It is mild in children, but is ready to be severe. If left untreated for a long time, the structure of the bronchi changes irreversibly and becomes ineffective. There are cases of death due to risk factors for irritability and asthma. In the first objective of the study, the National Center for Maternal and Child Health (NCMCH) Children's Counseling Polyclinic, Respiratory Pathology Department, and the Children's Department of the General Hospital of 21 aimags and 9 districts were used to determine the prevalence of Acute respiratory infections, implemented outpatient (2019-2021). Within the scope of objectives 2 and 3 of the study, a self-controlled case-control study model was used to assess the diagnosis of asthma in the case group based on the GINA-2018 guideline evaluation and clinical and laboratory tests based on the GINA protocol treatment. The parameters were taken, the pre-treatment parameters were recorded and compared in the control group, and the results were calculated. Results: When the prevalence was determined by the Acute respiratory infections level, there were 11 cases per 1,000 children. 80.8% of cases of asthma were caused by asthma 1-5 times a year, and the majority or 96.5% were aged 0-9 years. Allergies include plant (42.9%), food (25.4%), and pet (14.3%) allergies under the age of 4, all types of allergies between the ages of 5-14, and plant allergies 15-19 years, (9%), food (21.4%), pet (14.3%), environmental moisture and mold allergies (14.3%). Among the 89 children treated according to GINA guidelines, 64.0% used spices or allergenic foods, 13.5% used antibiotics, 6.7% used paracetamol, and 13.5% used other drugs. Children with asthma were assessed according to GINA guidelines and monitored and treated for 1 year (0.0001), the number of cases of asthma (p = 0.035) and the number of people receiving emergency care (p = 0.042) decreased statistically. There was a statistically significant difference of 2%, nocturnal cough decreased by 15.2%, and whooping cough decreased by 1.4%. Conclusions: The prevalence of asthma was 11 cases per 1,000 children. The main causes of allergies are plants, food and pets. The number of coughs, hospitalizations and emergency room visits decreased with GINA treatment.