Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a 5-year survival low of 2% in advanced cases. Despite being a fatal disease, there is a lack of a good predictor of prognosis which can aid in the management of patients. The tumor microenvironment of PDAC, including immune cells, plays a vital role in the progression and invasiveness of PDAC. Cluster of differentiation 47 (CD47) which has a “don’t eat me signal” to macrophages through receptor signal regulatory protein alpha, prevents immune cell surveillance of cancer cells. This contributes to the immune escape and invasiveness of cancer. Methods: We obtained pancreatic cancer tissue microarray samples from 98 patients treated in Hanyang University Hospital. The diagnosis was proven by a tissue biopsy obtained after surgical resection. Immunohistochemical staining was done using CD47 antibody. Data was analyzed using R software ver. 4.3.3. Results: In a study of 98 patients with PDAC, CD47 expression (54.1%) was significantly correlated with advanced disease stage. Positive CD47 expression was associated with lower overall survival (P = 0.028) and disease-free survival (P = 0.005) in all patients. In advanced-stage patients, CD47 remained a predictor of lower overall survival (P = 0.012) and diseasefree survival (P = 0.023). Multivariate analysis identified positive CD47 expression as an independent factor affecting overall survival (P = 0.048). These results emphasize CD47’s prognostic relevance in PDAC, particularly in advanced stages. Conclusion Positive CD47 expression in PDAC indicates an advanced stage of the disease and independently predicts poor outcomes. This highlights CD47’s role as a crucial prognostic marker in advanced PDAC stages.

Purpose: Transversus abdominis plane (TAP) block is a promising technique for postoperative pain control. In this study, we aimed to evaluate the efficacy of the TAP block in managing postoperative pain after laparoscopic totally extraperitoneal (TEP) inguinal hernia repair. Methods: In this retrospective study, medical records of patients who had received ultrasonography-guided TAP blocks after surgery from January 2019 to August 2023 were reviewed and compared with those of patients who had not received. Propensity score matching was controlled for age as a confounder. Postoperative pain levels were measured using the numeric rating scale (NRS). Results: After matching, 95 patients were included in each group. The TAP block group (2.7 vs. 4.0, P < 0.001) had significantly lower NRS scores immediately and early postoperative pain than the control group (1.9 vs. 2.5, P < 0.001). However, there was no significant difference between the 2 groups in terms of postoperative complications (P > 0.05). Conclusion TAP block is effective and safe for managing immediate and early postoperative pain in laparoscopic TEP inguinal hernia repair and does not increase the risk of complications.

BACKGROUND/OBJECTIVES: This study aimed to use plasma metabolites to identify clusters of breast cancer survivors and to compare their dietary characteristics and health-related factors across the clusters using unsupervised machine learning. SUBJECTS/METHODS: A total of 419 breast cancer survivors were included in this crosssectional study. We considered 30 plasma metabolites, quantified by high-throughput nuclear magnetic resonance metabolomics. Clusters were obtained based on metabolites using 4 different unsupervised clustering methods: k-means (KM), partitioning around medoids (PAM), self-organizing maps (SOM), and hierarchical agglomerative clustering (HAC). The t-test, χ2 test, and Fisher’s exact test were used to compare sociodemographic, lifestyle, clinical, and dietary characteristics across the clusters. P-values were adjusted through a false discovery rate (FDR). RESULTS: Two clusters were identified using the 4 methods. Participants in cluster 2 had lower concentrations of apolipoprotein A1 and large high-density lipoprotein (HDL) particles and smaller HDL particle sizes, but higher concentrations of chylomicrons and extremely large very-low-density-lipoprotein (VLDL) particles and glycoprotein acetyls, a higher ratio of monounsaturated fatty acids to total fatty acids, and larger VLDL particle sizes compared with cluster 1. Body mass index was significantly higher in cluster 2 compared with cluster 1 (FDR adjusted-PKM < 0.001; PPAM = 0.001; PSOM < 0.001; and PHAC = 0.043). CONCLUSION The breast cancer survivors clustered on the basis of plasma metabolites had distinct characteristics. Further prospective studies are needed to investigate the associations between metabolites, obesity, dietary factors, and breast cancer prognosis.

Background: Respiratory infections play a major role in acute exacerbation of chronic obstructive pulmonary disease (AECOPD). This study assessed the prevalence of bacterial and viral pathogens and their clinical impact on patients with AECOPD. Methods: This retrospective study included 1,186 patients diagnosed with AECOPD at 28 hospitals in South Korea between 2015 and 2018. We evaluated the identification rates of pathogens, basic patient characteristics, clinical features, and the factors associated with infections by potentially drug-resistant (PDR) pathogens using various microbiological tests. Results: Bacteria, viruses, and both were detected in 262 (22.1%), 265 (22.5%), and 129 (10.9%) of patients, respectively. The most common pathogens included Pseudomonas aeruginosa (17.8%), Mycoplasma pneumoniae (11.2%), Streptococcus pneumoniae (9.0%), influenza A virus (19.0%), rhinovirus (15.8%), and respiratory syncytial virus (6.4%). Notably, a history of pulmonary tuberculosis (odds ratio [OR], 1.66; p=0.046), bronchiectasis (OR, 1.99; p=0.032), and the use of a triple inhaler regimen within the past 6 months (OR, 2.04; p=0.005) were identified as significant factors associated with infection by PDR pathogens. Moreover, patients infected with PDR pathogens exhibited extended hospital stays (15.9 days vs. 12.4 days, p=0.018) and higher intensive care unit admission rates (15.9% vs. 9.5%, p=0.030). Conclusion This study demonstrates that a variety of pathogens are involved in episodes of AECOPD. Nevertheless, additional research is required to confirm their role in the onset and progression of AECOPD.

Purpose: The classification of asthma phenotypes frequently depends on the age of onset. However, the rationale for specific age cutoffs remains unclear. This study aimed to explore the distribution of asthma onset age, to define subgroups based on onset age, and to examine their characteristics within a broad Korean population. Methods: An analysis of cross-sectional data involving 56,632 participants from the Korean National Health and Nutrition Examination Survey (2010–2016) was conducted. Data on asthma history, including diagnosis, self-reported age of asthma onset, and current disease status, were collected using structured questionnaires. Results: The distribution of asthma onset age showed a distinct peak in early childhood, with a decline between the ages 15 and 20.Based on this distribution, asthma was categorized into childhood-onset ( ≤ 18 years) and adult-onset ( > 18 years) for further analysis.Multivariate analyses indicated that adult-onset asthma was associated with older age, female sex, obesity, and a history of smoking, whereas childhood-onset asthma was linked to younger age, male sex, allergic rhinitis, and atopic dermatitis. Among the adultonset group, current asthma had a later onset age, increased history of smoking history, and atopic dermatitis compared to past asthma. Conclusion This analysis of nationwide general population data suggests that an age threshold around 18 years may be relevant for defining adult-onset asthma.

Purpose: The classification of asthma phenotypes frequently depends on the age of onset. However, the rationale for specific age cutoffs remains unclear. This study aimed to explore the distribution of asthma onset age, to define subgroups based on onset age, and to examine their characteristics within a broad Korean population. Methods: An analysis of cross-sectional data involving 56,632 participants from the Korean National Health and Nutrition Examination Survey (2010–2016) was conducted. Data on asthma history, including diagnosis, self-reported age of asthma onset, and current disease status, were collected using structured questionnaires. Results: The distribution of asthma onset age showed a distinct peak in early childhood, with a decline between the ages 15 and 20.Based on this distribution, asthma was categorized into childhood-onset ( ≤ 18 years) and adult-onset ( > 18 years) for further analysis.Multivariate analyses indicated that adult-onset asthma was associated with older age, female sex, obesity, and a history of smoking, whereas childhood-onset asthma was linked to younger age, male sex, allergic rhinitis, and atopic dermatitis. Among the adultonset group, current asthma had a later onset age, increased history of smoking history, and atopic dermatitis compared to past asthma. Conclusion This analysis of nationwide general population data suggests that an age threshold around 18 years may be relevant for defining adult-onset asthma.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a 5-year survival low of 2% in advanced cases. Despite being a fatal disease, there is a lack of a good predictor of prognosis which can aid in the management of patients. The tumor microenvironment of PDAC, including immune cells, plays a vital role in the progression and invasiveness of PDAC. Cluster of differentiation 47 (CD47) which has a “don’t eat me signal” to macrophages through receptor signal regulatory protein alpha, prevents immune cell surveillance of cancer cells. This contributes to the immune escape and invasiveness of cancer. Methods: We obtained pancreatic cancer tissue microarray samples from 98 patients treated in Hanyang University Hospital. The diagnosis was proven by a tissue biopsy obtained after surgical resection. Immunohistochemical staining was done using CD47 antibody. Data was analyzed using R software ver. 4.3.3. Results: In a study of 98 patients with PDAC, CD47 expression (54.1%) was significantly correlated with advanced disease stage. Positive CD47 expression was associated with lower overall survival (P = 0.028) and disease-free survival (P = 0.005) in all patients. In advanced-stage patients, CD47 remained a predictor of lower overall survival (P = 0.012) and diseasefree survival (P = 0.023). Multivariate analysis identified positive CD47 expression as an independent factor affecting overall survival (P = 0.048). These results emphasize CD47’s prognostic relevance in PDAC, particularly in advanced stages. Conclusion Positive CD47 expression in PDAC indicates an advanced stage of the disease and independently predicts poor outcomes. This highlights CD47’s role as a crucial prognostic marker in advanced PDAC stages.

Purpose: Transversus abdominis plane (TAP) block is a promising technique for postoperative pain control. In this study, we aimed to evaluate the efficacy of the TAP block in managing postoperative pain after laparoscopic totally extraperitoneal (TEP) inguinal hernia repair. Methods: In this retrospective study, medical records of patients who had received ultrasonography-guided TAP blocks after surgery from January 2019 to August 2023 were reviewed and compared with those of patients who had not received. Propensity score matching was controlled for age as a confounder. Postoperative pain levels were measured using the numeric rating scale (NRS). Results: After matching, 95 patients were included in each group. The TAP block group (2.7 vs. 4.0, P < 0.001) had significantly lower NRS scores immediately and early postoperative pain than the control group (1.9 vs. 2.5, P < 0.001). However, there was no significant difference between the 2 groups in terms of postoperative complications (P > 0.05). Conclusion TAP block is effective and safe for managing immediate and early postoperative pain in laparoscopic TEP inguinal hernia repair and does not increase the risk of complications.

Background: This study analyzed the epidemiology and treatment outcomes of germ cell tumorpatients at a single institution. Methods: A retrospective analysis was conducted on intracranial germ cell tumor (iGCT) pa-tients treated at a single tertiary hospital from 2004 to 2019. Patients were categorized based on treatment modality: Korean Society for Pediatric Neuro-Oncology (KSPNO) protocol or bleomycin, etoposide, and cisplatin with radiation therapy. Results: Forty-nine iGCT patients treated with combined chemotherapy and radiotherapywere analyzed. The median age was 19 years (range: 6–40), with a median follow-up duration of 148.0 months (range: 10.5–265.5). Tumors were most common in the pineal gland (51.0%). Although no significant differences in outcomes were observed between treatment modalities, outcomes varied significantly by pathological type. The 10-year progression-free survival rates for germinoma and non-germinomatous germ cell tumors (NGGCTs) were 88.1% and 32.7%, respectively (p=0.003), while the 10-year overall survival rates were 92.9% and 67.5%, respectively (p<0.001). Fourteen patients experienced CTCAE (Common Terminology Criteria for Adverse Events) grade ≥3 adverse events, with one eventrelated death. Conclusion Pure germinoma demonstrated higher survival and lower recurrence rates comparedto NGGCT. The KSPNO protocol appears to be an acceptable and safe treatment option for iGCT patients. Further multi-institutional studies with larger cohorts are warranted.

BACKGROUND/OBJECTIVES: This study aimed to use plasma metabolites to identify clusters of breast cancer survivors and to compare their dietary characteristics and health-related factors across the clusters using unsupervised machine learning. SUBJECTS/METHODS: A total of 419 breast cancer survivors were included in this crosssectional study. We considered 30 plasma metabolites, quantified by high-throughput nuclear magnetic resonance metabolomics. Clusters were obtained based on metabolites using 4 different unsupervised clustering methods: k-means (KM), partitioning around medoids (PAM), self-organizing maps (SOM), and hierarchical agglomerative clustering (HAC). The t-test, χ2 test, and Fisher’s exact test were used to compare sociodemographic, lifestyle, clinical, and dietary characteristics across the clusters. P-values were adjusted through a false discovery rate (FDR). RESULTS: Two clusters were identified using the 4 methods. Participants in cluster 2 had lower concentrations of apolipoprotein A1 and large high-density lipoprotein (HDL) particles and smaller HDL particle sizes, but higher concentrations of chylomicrons and extremely large very-low-density-lipoprotein (VLDL) particles and glycoprotein acetyls, a higher ratio of monounsaturated fatty acids to total fatty acids, and larger VLDL particle sizes compared with cluster 1. Body mass index was significantly higher in cluster 2 compared with cluster 1 (FDR adjusted-PKM < 0.001; PPAM = 0.001; PSOM < 0.001; and PHAC = 0.043). CONCLUSION The breast cancer survivors clustered on the basis of plasma metabolites had distinct characteristics. Further prospective studies are needed to investigate the associations between metabolites, obesity, dietary factors, and breast cancer prognosis.