suggest that some reproductive factors associated with BC differ across ethnicities and time trends, perhaps due to the prevalence of reproductive factors and the baseline hazard of BC.

Purpose: Breast cancer gene (BRCA) mutation is a well-known risk factor for breast cancer, and clinical interest in prophylactic mastectomy has increased in recent years.We investigated patients who were BRCA mutation carriers and underwent contralateral risk-reducing mastectomy (RRM), focusing on the incidence of occult malignancy after contralateral RRM. Methods: Prospectively collected data of patients with breast cancer treated at a single institution were retrospectively reviewed. Patients who underwent RRM with BRCA mutation who underwent RRM between January 2010 and November 2023 were included in this study.Among patients who underwent contralateral RRM, those with a primary cancer diagnosis were included, and those with occult malignancy on the contralateral RRM side were reviewed additionally. The demographics and pathologies of both primary breast cancer and occult malignancies were evaluated. Results: In our institution, 925 patients were identified as BRCA mutation carriers, and 320 patients underwent contralateral RRM along with primary breast cancer surgery. BRCA2 mutation occurred more frequently (54.8%) in the overall BRCA mutation cohort. Furthermore, we reviewed 320 patients diagnosed with breast cancer and detected as BRCA mutation carriers who underwent contralateral RRM; high proportion of them were BRCA1 mutation carriers.Interestingly, we found a low incidence of only seven patients (2.2%) with occult malignancy on contralateral RRM side, which is different from that reported in other nations. Conclusion The incidence of occult malignancy in the contralateral breast of breast cancer patients with breast cancer with BRCA mutation is significantly low, and may be influenced by several factors. Increased utilization of screening and advancements in diagnostic technologies in South Korea have reduced the chance of occult malignancy in RRM, and a variety of pathologic examination methods may affect the rate of incidence.

Purpose: Breast cancer gene (BRCA) mutation is a well-known risk factor for breast cancer, and clinical interest in prophylactic mastectomy has increased in recent years.We investigated patients who were BRCA mutation carriers and underwent contralateral risk-reducing mastectomy (RRM), focusing on the incidence of occult malignancy after contralateral RRM. Methods: Prospectively collected data of patients with breast cancer treated at a single institution were retrospectively reviewed. Patients who underwent RRM with BRCA mutation who underwent RRM between January 2010 and November 2023 were included in this study.Among patients who underwent contralateral RRM, those with a primary cancer diagnosis were included, and those with occult malignancy on the contralateral RRM side were reviewed additionally. The demographics and pathologies of both primary breast cancer and occult malignancies were evaluated. Results: In our institution, 925 patients were identified as BRCA mutation carriers, and 320 patients underwent contralateral RRM along with primary breast cancer surgery. BRCA2 mutation occurred more frequently (54.8%) in the overall BRCA mutation cohort. Furthermore, we reviewed 320 patients diagnosed with breast cancer and detected as BRCA mutation carriers who underwent contralateral RRM; high proportion of them were BRCA1 mutation carriers.Interestingly, we found a low incidence of only seven patients (2.2%) with occult malignancy on contralateral RRM side, which is different from that reported in other nations. Conclusion The incidence of occult malignancy in the contralateral breast of breast cancer patients with breast cancer with BRCA mutation is significantly low, and may be influenced by several factors. Increased utilization of screening and advancements in diagnostic technologies in South Korea have reduced the chance of occult malignancy in RRM, and a variety of pathologic examination methods may affect the rate of incidence.

Purpose: Breast cancer gene (BRCA) mutation is a well-known risk factor for breast cancer, and clinical interest in prophylactic mastectomy has increased in recent years.We investigated patients who were BRCA mutation carriers and underwent contralateral risk-reducing mastectomy (RRM), focusing on the incidence of occult malignancy after contralateral RRM. Methods: Prospectively collected data of patients with breast cancer treated at a single institution were retrospectively reviewed. Patients who underwent RRM with BRCA mutation who underwent RRM between January 2010 and November 2023 were included in this study.Among patients who underwent contralateral RRM, those with a primary cancer diagnosis were included, and those with occult malignancy on the contralateral RRM side were reviewed additionally. The demographics and pathologies of both primary breast cancer and occult malignancies were evaluated. Results: In our institution, 925 patients were identified as BRCA mutation carriers, and 320 patients underwent contralateral RRM along with primary breast cancer surgery. BRCA2 mutation occurred more frequently (54.8%) in the overall BRCA mutation cohort. Furthermore, we reviewed 320 patients diagnosed with breast cancer and detected as BRCA mutation carriers who underwent contralateral RRM; high proportion of them were BRCA1 mutation carriers.Interestingly, we found a low incidence of only seven patients (2.2%) with occult malignancy on contralateral RRM side, which is different from that reported in other nations. Conclusion The incidence of occult malignancy in the contralateral breast of breast cancer patients with breast cancer with BRCA mutation is significantly low, and may be influenced by several factors. Increased utilization of screening and advancements in diagnostic technologies in South Korea have reduced the chance of occult malignancy in RRM, and a variety of pathologic examination methods may affect the rate of incidence.

Purpose: Triple-negative breast cancer (TNBC) is a heterogeneous and aggressive subtype of breast cancer associated with poor clinical outcomes. Although programmed death ligand 1 (PD-L1) expression has emerged as both a prognostic and predictive biomarker, its utility remains limited, especially in PD-L1-negative tumors. The identification of additional molecular markers is crucial for improving prognostic stratification and guiding treatment strategies. Methods: Formalin-fixed, paraffin-embedded tumor tissues from 38 patients with TNBC were analyzed. PD-L1 expression was assessed using immunohistochemistry and categorized as positive or negative. Whole-exome sequencing was performed, and somatic variants were analyzed using Maftools. Mutational signatures were compared with the Catalogue Of Somatic Mutations In Cancer reference profiles. Survival analyses were performed to evaluate the prognostic significance of the identified variants. Results: Mutational landscape analysis revealed that C>T and G>A transitions were the most frequent base substitutions. PD-L1-negative tumors exhibited a predominance of single-base substitution (SBS) 5, whereas PD-L1-positive tumors resembled SBS6, reflecting potential differences in the underlying mutational processes. Comparative analysis identified 12 PD-L1-negative-specific and seven PD-L1-positive-specific variants. Among PD-L1-negative tumors, mutations in ANGPTL5 and KIAA1549L were significantly associated with worse overall survival. Conclusion Our findings highlight distinct mutational profiles and prognostic variants according to PD-L1 status in TNBC. ANGPTL5 and KIAA1549L variants may serve as potential prognostic markers for PD-L1-negative tumors. These results underscore the value of incorporating genomic information to refine the prognostic stratification of TNBC.

Objectives: . The supine sleep position and the rapid eye movement (REM) stage are widely recognized to exacerbate the severity of obstructive sleep apnea (OSA). Position-dependent OSA is generally characterized by an apnea-hypopnea index (AHI) that is at least twice as high in the supine position compared to other sleep positions. However, this condition can be misdiagnosed if a particular sleep stage—REM or non-REM (NREM)—predominates in a specific position. We explored the impact of the sleep stage on positional dependency in OSA. Methods: . Polysomnographic data were retrospectively analyzed from 111 patients with OSA aged 18 years or older, all of whom had an AHI exceeding five events per hour and slept in both supine and non-supine positions for at least 5% of the total sleep time. The overall ratio of non-supine AHI to supine AHI (NS/S-AHI ratio) was compared between total, REM, and NREM sleep. Additionally, a weighted NS/S-AHI ratio, reflecting the proportion of time spent in each sleep stage, was calculated and compared to the original ratio. Results: . The mean NS/S-AHI ratio was consistent between the entire sleep period and the specific sleep stages. However, the NS/S-AHI ratios for individual patients displayed poor agreement between total sleep and the specific stages. Additionally, the weighted NS/S-AHI ratio displayed poor agreement with the original NS/S-AHI ratio, primarily due to discrepancies in patients with mild to moderate OSA. Conclusion . The weighted NS/S-AHI ratio may help precisely assess positional dependency.

Objective: The emergency department (ED) serves as the initial point of contact for many sepsis patients, but crowding can affect the timely delivery of essential interventions, such as antibiotics. This paper explores the relationship between antibiotics administration and ED crowding in the context of sepsis management. Methods: This single-center study at a tertiary care hospital included adult patients aged 18 and above who visited the emergency department from January 2018 to December 2022. Patients showing signs of septic shock upon arrival were selected as the study population. This study examined factors such as emergency department occupancy, antibiotic administration time, and their correlation with timely antibiotic treatment. Results: This study of 839 adult patients with septic shock found a weak correlation (P=0.107) between the time to antibiotic administration and department occupancy. Delayed antibiotic administration was observed when the occupancy exceeded 100%. On the other hand, there was no significant correlation between antibiotic administration within one hour and department occupancy. Conclusion Various factors, such as ED bed occupancy, medical staffing, resource allocation, and patient acuity, must be considered when comprehensively evaluating the impact of ED overcrowding on treating septic shock and other conditions.

Purpose: We aimed to investigate changes in visiting patterns after the lifting of mask mandates in a single pediatric emergency medical center in Seoul, Korea. Methods: This retrospective study was based on the data of patients’ (≤ 18 years) visits to the emergency department (ED) of the center from January 1, 2022 through June 30, 2023. Clinical characteristics, Korean Triage and Acuity Scale (KTAS) level, ED outcomes, and length of stay were compared between before (March 20-June 30, 2022) and after (March 20-June 30, 2023) the lifting of mask mandates. The comparisons were iterated in the patients with infectious disease. Results: During the study period, a total of 18,654 children visited the ED. After the lifting of mask mandates, ED visits increased from 7,146 to 11,508 (61.0%; 95% confidence interval, 59.5-62.6; P < 0.001). The increase was more prominent in the age of 2-5 years (82.9%), infectious diseases (175.3%), KTAS level 3 (127.7%), and length of stay shorter than 3 hours (78.8%-92.6%). The number of patients per hour increased by 151.2% for 5 patients or more and over 3,000% for 10 or more. Median length of stay decreased (2.3 hours [interquartile range, 1.2-4.1] to 1.9 hours [1.1-3.5]; P < 0.001). The patients with infectious disease (n = 7,139) showed similar patterns of increase in the age of 2-5 years, KTAS level 3, and length of stay shorter than 3 hours, with an additional increase in the age of 6-18 years. Conclusion After the lifting of mask mandates, pediatric visits increased by 61%, with the highest increase in children with mild infectious diseases on weekends and at night, and the proportion of more than 10 visits per hour significantly increased. We need urgent and realistic support measures from health authorities.

Purpose: This study was performed to analyze clinical features and use of renal replacement therapy (RRT) for children who visit the pediatric emergency department with benign acute childhood myositis (BACM) or rhabdomyolysis. Methods: We retrospectively reviewed medical records of 289 children who visited the emergency department with BACM or rhabdomyolysis from January 2013 through December 2022. Clinical features, laboratory and microbiological findings, and outcomes were compared between children with the two diagnoses. Subsequently, multivariable logistic regressions were performed to identify factors associated with applying RRT. Results: Of the 289 children, a total of 212 were analyzed, including 93 with BACM and 119 with rhabdomyolysis. Influenza (70 of the 145 children [48.3%]) was the most common cause, followed by exercise (36 of 212 [17.0%]). Compared with the children with BACM, those with rhabdomyolysis showed significantly higher frequencies of being boys and hematuria, and higher concentrations of hemoglobin, creatinine, creatine kinase, and myoglobin. Continuous venovenous hemofiltration, a modality of RRT, was applied to 8 children (6.7%) with rhabdomyolysis, of whom 1 died. Creatine kinase was independently associated with the application of RRT (adjusted odds ratio, 1.06; 95% confidence interval, 1.00-1.12; P = 0.036). Conclusion Rhabdomyolysis in children who require RRT may be associated with a higher concentration of creatine kinase.

These guidelines aim to establish the standard practice for diagnosing and treating patients with differentiated thyroid cancer (DTC). Based on the Korean Thyroid Association (KTA) Guidelines on DTC management, the “Treatment of Advanced DTC” section was revised in 2024 and has been provided through this chapter. Especially, this chapter covers surgical and nonsurgical treatments for the local (previous surgery site) or regional (cervical lymph node metastasis) recurrences. After drafting the guidelines, it was finalized by collecting opinions from KTA members and related societies. Surgical resection is the preferred treatment for local or regional recurrence of advanced DTC. If surgical resection is not possible, nonsurgical resection treatment under ultrasonography guidance may be considered as an alternative treatment for local or regional recurrence of DTC. Furthermore, if residual lesions are suspected even after surgical resection or respiratory-digestive organ invasion, additional radioactive iodine and external radiation treatments are considered.