1.Clinical Utility of Monitoring Circulating Tumor DNA Using a Targeted Next-generation Sequencing Panel in Patients with Colorectal Cancer
Hyoeun SHIM ; Soobeen HEO ; Jiyu SUN ; Moon Ki CHOI ; Sung Chan PARK ; Chang Won HONG ; Seong Hoon KIM ; Seog-Yun PARK ; Sun-Young KONG ; Ji Yeon BAEK
Annals of Laboratory Medicine 2025;45(4):450-458
Background:
Circulating tumor DNA (ctDNA) profiling from peripheral blood allows relatively noninvasive monitoring of solid tumors; however, its utility post-surgery or chemotherapy in colorectal cancer remains underexplored. We evaluated the clinical implications of a ctDNA next-generation sequencing (NGS) panel post-surgery or chemotherapy in patients with colorectal cancer.
Methods:
We collected samples from 23 patients with colorectal cancer (17 men, median age 65 yrs) at baseline and post-surgery or chemotherapy at the National Cancer Center, Korea, between January 2021 and September 2023. ctDNA was analyzed using an NGS panel including 46 genes, and variant allele frequencies (VAFs) were determined. Followup samples were analyzed using the NGS panel or droplet digital PCR (ddPCR) when probes were available. Clinical status was compared with ctDNA results, and survival was analyzed using a time-dependent Cox model.
Results:
Mutations were identified in 13 out of 14 patients (92.8%) with stage II/III cancer and in all nine patients (100%) with stage IV cancer. Mutations were detected in KRAS (N = 15, 65%), APC (N = 8, 35%), TP53 (N = 7, 30%), PIK3CA (N = 5, 22%), and RET (N = 4, 17%). A 1% increase in KRAS and TP53 VAFs was associated with 48% and 32% increased mortality risk, respectively. Changes in VAF correlated well with clinical findings.
Conclusions
The detection of and an increase in KRAS and TP53 VAFs were associated with poor prognosis. ddPCR-based ctDNA monitoring results were comparable to those obtained with the NGS panel. ctDNA monitoring during treatment is clinically informative in managing colorectal cancer.
2.Systemic Inflammatory Response Following Preoperative Chemoradiotherapy Can Affect Oncologic Outcomes in MSI-H/dMMR Rectal Cancer
Hyukjin CHOI ; Jin Ho BAEK ; An Na SEO ; Su Yeon PARK ; Hye Jin KIM ; Jun Seok PARK ; Gyu Seog CHOI ; Jong Gwang KIM ; Byung Woog KANG
Chonnam Medical Journal 2024;60(2):105-112
Systemic inflammatory response (SIR) is a crucial determinant of disease progression and survival in patients with colorectal cancer. This study investigated the prognostic relevance of changes in the platelet count on survival and the predictive value of changes in the platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) on the pathological tumor response to preoperative chemoradiotherapy (CRT) in patients with microsatellite instability-high (MSI-H) rectal cancer. From 2011 to 2022, data of 46 consecutive patients with MSI-H rectal cancer who were treated with preoperative CRT followed by curative surgery at Kyungpook National University Chilgok Hospital (Daegu, South Korea) were retrospectively analyzed. A 235 cut-off value was used to define whether PLR was high or low. Any change in the PLR or NLR was calculated on the basis of subtracting the pre-CRT PLR or NLR from the post-CRT values. Both pre-CRT and post-CRT values of the NLR and PLR were not significantly associated with clinical outcomes. Simple logistic regression analysis showed that a change in the PLR following CRT was not significantly associated with survival outcomes; however, patients who maintained a high change in the PLR following CRT showed significantly better pathologic T-stage. No statistically significant association was noted between changes in the platelet count and clinical outcomes of patients. The results suggested that changes in the PLR following CRT are associated with pathologic T-stage of the group. However, the SIR markers showed no prognostic values on the survival outcomes of the patients with MSI-H/mismatch repair-deficient (dMMR) locally advanced rectal cancer (LARC).
3.Resilience Gap in Gastrointestinal Endoscopy Activity during the COVID-19 Pandemic in South Korea
Hye-Yeon KIM ; Jeong-Ho YANG ; Sun-Seog KWEON
Chonnam Medical Journal 2024;60(3):180-186
This study assessed the impact of distancing measures during the COVID-19 pandemic on cancer diagnostic activities, including gastrointestinal endoscopy (GIE). It analyzed GIE volumes from 2020 to 2022 in comparison to 2018-2019, considering variations in resilience linked to socioeconomic status (SES). The analysis utilized data from the Korean Health Insurance Review and Assessment Services database, covering the entire population and medical facilities. Diagnostic GIE rates (2018-2022) in Gwangju Metropolitan City and Jeonnam province were examined, comparing age-standardized rates (ASRs) by area, gender, and SES. The results indicated a decline in ASRs for colonoscopy and endoscopic gastroduodenoscopy (EGD) in 2020 compared to 2018-2019, followed by an increase in 2021-2022, except for EGD in the medical aid population.SES based and rural-urban disparities were evident in the recovery of GIE rates. The findings suggest that equity-focused strategies are needed to ensure equitable healthcare access among different socioeconomic groups after pandemic.
4.MR Template‑Based Individual Brain PET Volumes‑of‑Interest Generation Neither Using MR nor Using Spatial Normalization
Seung Yeon SEO ; Jungsu S. OH ; Jinwha CHUNG ; Seog‑Young KIM ; Jae Seung KIM
Nuclear Medicine and Molecular Imaging 2023;57(2):73-85
For more anatomically precise quantitation of mouse brain PET, spatial normalization (SN) of PET onto MR template and subsequent template volumes-of-interest (VOIs)-based analysis are commonly used. Although this leads to dependency on the corresponding MR and the process of SN, routine preclinical/clinical PET images cannot always afford corresponding MR and relevant VOIs. To resolve this issue, we propose a deep learning (DL)-based individual-brain-specific VOIs (i.e., cortex, hippocampus, striatum, thalamus, and cerebellum) directly generated from PET images using the inverse-spatialnormalization (iSN)-based VOI labels and deep convolutional neural network model (deep CNN). Our technique was applied to mutated amyloid precursor protein and presenilin-1 mouse model of Alzheimer’s disease. Eighteen mice underwent T2-weighted MRI and 18 F FDG PET scans before and after the administration of human immunoglobin or antibody-based treatments. To train the CNN, PET images were used as inputs and MR iSN-based target VOIs as labels. Our devised methods achieved decent performance in terms of not only VOI agreements (i.e., Dice similarity coefficient) but also the correlation of mean counts and SUVR, and CNN-based VOIs was highly accordant with ground-truth (the corresponding MR and MR template-based VOIs). Moreover, the performance metrics were comparable to that of VOI generated by MR-based deep CNN. In conclusion, we established a novel quantitative analysis method both MR-less and SN-less fashion to generate individual brain space VOIs using MR template-based VOIs for PET image quantification.
5.Efficacy of air leak test in detection of anastomotic leaks after rectal excision: a retrospective case-controlled study
Seung Ho SONG ; Jun Seok PARK ; Gyu-Seog CHOI ; Soo Yeon PARK ; Hye Jin KIM ; Sung-Min LEE ; Dong-Hee NA ; Min Hye JEONG
Annals of Surgical Treatment and Research 2023;104(4):214-221
Purpose:
Although its efficacy is uncertain, an intraoperative air leak test (ALT) is commonly used to detect mechanical defects following bowel anastomosis. This study aimed to evaluate the efficacy of ALT to detect anastomotic leakage (AL) following rectal excision.
Methods:
We reviewed our database for patients with rectal cancers who had undergone curative surgery between January 2012 and January 2018. Patients were grouped according to whether or not an ALT was performed. Propensity score analyses were performed to compare outcomes for groups in a 1:1 case-matched cohort.
Results:
In total, 1,191 patients underwent rectal excision; 438 (219 in each group) formed the case-matched cohort for analysis. The protective stoma rate was 16.0% and 14.6% in the ALT and the no-ALT groups, respectively (P = 0.791). In the ALT group, 2 patients (0.9%) showed a positive result and were treated with rectal tube drainage, resulting in no leakage.There was no significant difference in postoperative AL rate between the groups (ALT group: 4.6% vs. no-ALT group: 4.1%, P > 0.999).
Conclusion
ALT played a minimal role in detecting AL following rectal excision. Further studies are warranted to validate our results and clarify whether AL can be prevented with ALT or alternative methods.
6.Association Between Serum Bilirubin and Atrial Fibrillation: A Mendelian Randomization Study
Si-Woo KIM ; Jung-Ho YANG ; Sun-Seog KWEON ; Young-Hoon LEE ; Seong-Woo CHOI ; So-Yeon RYU ; Hae-Sung NAM ; Hye-Yeon KIM ; Min-Ho SHIN
Korean Circulation Journal 2023;53(7):472-479
Background and Objectives:
The association between bilirubin and atrial fibrillation (AF) has been evaluated previously in observational studies but with contradictory results. This study evaluated the causal association between serum bilirubin level and AF using Mendelian randomization (MR) analysis.
Methods:
This cross-sectional study includes 8,977 participants from the Dong-gu Study.In the observational analysis, multivariate logistic regression was performed to evaluate the association between bilirubin and prevalent AF. To evaluate the causal association between bilirubin and AF, MR analysis was conducted by using the UGT1A1 rs11891311 and rs4148323 polymorphisms as instrumental variables.
Results:
Elevated serum bilirubin levels were associated with an increased risk for AF in observational analysis (total bilirubin: odds ratio [OR], 1.31; 95% confidence interval [95% CI], 1.15–1.48 per 1 standard deviation [SD]; direct bilirubin: OR, 1.31; 95% CI, 1.18–1.46 per 1 SD), whereas the genetically predicted serum bilirubin levels in MR analysis did not show this association (total bilirubin: OR, 1.02; 95% CI, 0.67–1.53 per 1 SD; direct bilirubin: OR, 1.03; 95% CI, 0.61–1.73 per 1 SD).
Conclusions
Genetically predicted bilirubin levels were not associated with prevalent AF.Thus, the observational association between serum bilirubin levels and AF may be noncausal and affected by reverse causality or unmeasured confounding.
7.Association Between Plasma Homocysteine Level and Mortality:A Mendelian Randomization Study
Chang Kyun CHOI ; Sun-Seog KWEON ; Young-Hoon LEE ; Hae-Sung NAM ; Seong-Woo CHOI ; Hye-Yeon KIM ; Min-Ho SHIN
Korean Circulation Journal 2023;53(10):710-719
Background and Objectives:
In previous studies, high homocysteine levels were associated with high cardiovascular mortality. However, these results were inconsistent with those of randomized controlled trials. We aimed to evaluate the causal role of homocysteine on allcause and cardiovascular mortality using Mendelian randomization (MR) analysis.
Methods:
This study included the 10,005 participants in the Namwon Study. In conventional observational analysis, age, sex, survey years, lifestyles, body mass index, comorbidities, and serum folate level were adjusted using multivariate Cox proportional regression. MR using 2-stage least squares regression was used to evaluate the association between genetically predicted plasma homocysteine levels and mortality. Age, sex, and survey years were adjusted for each stage. The methylenetetrahydrofolate reductase (MTHFR) polymorphism was used as an instrumental variable for predicting plasma homocysteine levels.
Results:
Observed homocysteine levels were positively associated with all-cause (hazard ratio [HR], 1.40; 95% confidence interval [CI], 1.26–1.54) and cardiovascular (HR, 1.62; 95% CI, 1.28–2.06) mortality when plasma homocysteine levels doubled. However, these associations were not significant in MR analysis. The HRs of doubling genetically predicted plasma homocysteine levels for all-cause and cardiovascular mortality were 0.99 (95% CI, 0.62–1.57) and 1.76 (95% CI, 0.54–5.77), respectively.
Conclusions
This MR analysis did not support a causal role for elevated plasma homocysteine concentrations in premature deaths.
8.Effect Modification of Kidney Function on the Non-linear Association Between Serum Calcium Levels and Cardiovascular Mortality in Korean Adults
Jung-Ho YANG ; Sun-Seog KWEON ; Young-Hoon LEE ; Seong-Woo CHOI ; So-Yeon RYU ; Hae-Sung NAM ; Hye-Yeon KIM ; Min-Ho SHIN
Journal of Preventive Medicine and Public Health 2023;56(3):282-290
Objectives:
This study aimed to evaluate the potential interaction between kidney function and the non-linear association between serum calcium levels and cardiovascular disease (CVD) mortality.
Methods:
This study included 8927 participants enrolled in the Dong-gu Study. Albumin-corrected calcium levels were used and categorized into 6 percentile categories: <2.5th, 2.5-25.0th, 25.0-50.0th, 50.0-75.0th, 75.0-97.5th, and >97.5th. Restricted cubic spline analysis was used to examine the non-linear association between calcium levels and CVD mortality. Cox proportional hazard regression was used to estimate hazard ratios (HRs) for CVD mortality according to serum calcium categories. All survival analyses were stratified by the estimated glomerular filtration rate.
Results:
Over a follow-up period of 11.9±2.8 years, 1757 participants died, of whom 219 died from CVD. A U-shaped association between serum calcium and CVD mortality was found, and the association was more evident in the low kidney function group. Compared to the 25.0-50.0th percentile group for serum calcium levels, both low and high serum calcium tended to be associated with CVD mortality (<2.5th: HR, 6.23; 95% confidence interval [CI], 1.16 to 33.56; >97.5th: HR, 2.56; 95% CI, 0.76 to 8.66) in the low kidney function group. In the normal kidney function group, a similar association was found between serum calcium levels and CVD mortality (<2.5th: HR, 1.37; 95% CI, 0.58 to 3.27; >97.5th: HR, 1.65; 95% CI, 0.70 to 3.93).
Conclusions
We found a non-linear association between serum calcium levels and CVD mortality, suggesting that calcium dyshomeostasis may contribute to CVD mortality, and kidney function may modify the association.
9.Seroma prevention with topical Abnobaviscum sclerotherapy following excision of giant cervical lipoma
Jun Ho CHOI ; Seung Yeon CHOI ; Jae Ha HWANG ; Kwang Seog KIM ; Sam Yong LEE
Archives of Craniofacial Surgery 2023;24(1):10-17
Background:
Lipomas are common benign tumors of mesenchymal origin that are composed of mature adipocytes. Giant lipomas have a diameter ≥ 10 cm in one or more dimensions or weigh at least 1,000 g. The surgical excision of a giant lipoma requires extensive dissection, increasing the risk of a seroma, which can cause surgical site complications such as wound infection and necrosis. Sclerotherapy with Abnobaviscum (Viscum album extract) is a relatively new technique used to reduce malignant pleural effusion. In this study, we evaluated the effectiveness of prophylactic sclerotherapy using Abnobaviscum to decrease seroma after giant lipoma excision.
Methods:
We conducted a retrospective medical record review of patients who underwent surgical excision for giant lipoma of the neck from January 2019 to December 2022. Sclerotherapy was performed on the first postoperative day in patients who consented to the procedure, and Abnobaviscum was instilled through the existing Hemovac drain. We compared the clinical course between those who underwent postoperative sclerotherapy and those who did not.
Results:
Among the 30 patients who underwent giant lipoma excision, we applied sclerotherapy with Abnobaviscum to 15 patients. The average time from surgery to Hemovac removal was statistically shorter in patients who underwent sclerotherapy (p= 0.004). Furthermore, seroma formation was significantly reduced in patients receiving sclerotherapy (p= 0.003).
Conclusion
In patients undergoing giant lipoma excision, sclerotherapy using Abnobaviscum helps reduce postoperative seroma formation during the initial postoperative period. It can be an excellent method to reduce complications related to seroma and attenuate patients’ postoperative burden.
10.Circulating Tumor DNA–Based Genotyping and Monitoring for Predicting Disease Relapses of Patients with Peripheral T-Cell Lymphomas
Seok Jin KIM ; Yeon Jeong KIM ; Sang Eun YOON ; Kyung Ju RYU ; Bon PARK ; Donghyun PARK ; Duck CHO ; Hyun-Young KIM ; Junhun CHO ; Young Hyeh KO ; Woong-Yang PARK ; Won Seog KIM
Cancer Research and Treatment 2023;55(1):291-303
Purpose:
Plasma circulating tumor DNA (ctDNA) could reflect the genetic alterations present in tumor tissues. However, there is little information about the clinical relevance of cell-free DNA genotyping in peripheral T-cell lymphoma (PTCL).
Materials and Methods:
After targeted sequencing plasma cell-free DNA of patients with various subtypes of PTCL (n=94), we analyzed the mutation profiles of plasma ctDNA samples and their predictive value of dynamic ctDNA monitoring for treatment outcomes.
Results:
Plasma ctDNA mutations were detected in 53 patients (56%, 53/94), and the detection rate of somatic mutations was highest in angioimmunoblastic T-cell lymphoma (24/31, 77%) and PTCL, not otherwise specified (18/29, 62.1%). Somatic mutations were detected in 51 of 66 genes that were sequenced, including the following top 10 ranked genes: RHOA, CREBBP, KMT2D, TP53, IDH2, ALK, MEF2B, SOCS1, CARD11, and KRAS. In the longitudinal assessment of ctDNA mutation, the difference in ctDNA mutation volume after treatment showed a significant correlation with disease relapse or progression. Thus, a ≥ 1.5-log decrease in genome equivalent (GE) between baseline and the end of treatment showed a significant association with better survival outcomes than a < 1.5-log decrease in GE.
Conclusion
Our results suggest the clinical relevance of plasma ctDNA analysis in patients with PTCL. However, our findings should be validated by a subsequent study with a larger study population and using a broader gene panel.

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