Hyeong-seok Nam

Dr. Hyeong-seok Nam


Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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Verified
Journal Article
Open access
PDF file
DRDaeGon Ryu
DaeGon Ryu
SKSu-Jin Kim
Su-Jin Kim
CCCheol Woong Choi
Cheol Woong Choi
SPSu Bum Park
Su Bum Park
HNHyeong-seok Nam
Hyeong-seok Nam
SHSun-Hwi Hwang
Sun-Hwi Hwang
Endoscopic submucosal dissection (ESD) is considered the treatment of choice for early gastric cancer (EGC) with a negligible risk of lymph node metastasis. Locally recurrent lesions on artificial ulcer scars are difficult to manage. Predicting the risk of local recurrence after ESD is important to manage and prevent the event. We aimed to elucidate the risk factors associated with local recurrence after ESD of EGC. Between November 2008 and February 2016, consecutive patients (n = 641; mean age, 69.3 ± 9.5 years; men, 77.2%) with EGC who underwent ESD at a single tertiary referral hospital were retrospectively analyzed to evaluate the incidence and factors associated with local recurrence. Local recurrence was defined as the development of neoplastic lesions at or adjacent to the site of the post-ESD scar. En bloc and complete resection rates were 97.8% and 93.6%, respectively. The local recurrence rate after ESD was 3.1%. The mean follow-up period after ESD was 50.7 ± 32.5 months. One case of gastric cancer-related death (0.15%) was noted, wherein the patient had refused additive surgical resection after ESD for EGC with lymphatic and deep submucosal invasion. Lesion size ≥15 mm, incomplete histologic resection, undifferentiated adenocarcinoma, scar, and the absence of erythema of the surface were associated with a higher risk of local recurrence. Predicting local recurrence during regular endoscopic surveillance after ESD is important, especially in patients with a larger lesion size (≥15 mm), incomplete histologic resection, surface changes of scars, and no erythema of the surface.

4 May 2019 in Scandinavian Journal of Gastroenterology
Verified
Journal Article
Closed access
JGJa Jun Goo
Ja Jun Goo
DRDae Gon Ryu
Dae Gon Ryu
HKHyung Wook Kim
Hyung Wook Kim
SPSu Bum Park
Su Bum Park
DKDae Hwan Kang
Dae Hwan Kang
BPByung Soo Park
Byung Soo Park
Objective: Adequate lymph node harvest (LNH) in colorectal cancer is closely related to survival. This study aimed to evaluate the effect of preoperative colonoscopic tattooing (PCT) with indocyanine green (ICG) on adequate LNH in colorectal cancer. Materials and methods: A total of 1079 patients who underwent surgical resection for colorectal cancer were divided into two groups: a tattooing group and a non-tattooing group. The patients were retrospectively analyzed for the number and adequacy of LNH according to tumor locations and stages. Univariate and multivariate analysis for factors associated with adequate LNH were done. Results: There was no significant difference between the two groups in the number and adequacy of LNH according to tumor locations. However, T1 colorectal cancer in the tattooing group had significantly higher adequate LNH (91.6% vs 82.1%, OR 2.370, p = .048) and T1 and N0 rectal cancer in the tattooing group also had higher adequate LNH although there was no statistical significance (100% vs 82.4%, OR 12.088, p = .095; 96.9% vs 84.8%, OR 5.570, p = .099) when compared to the non-tattooing group. Male sex and T1 stage were significantly associated with inadequate LNH in multivariate analysis (OR 0.556 (95% CI 0.340–0.909), p = .019; OR 0.555 (95% CI 0.339–0.910), p = .019, respectively). Conclusion: PCT with ICG did not improve adequate LNH in colorectal cancer but effectively improved adequate LNH in early colorectal cancer. Male sex and early cancer were risk factors for inadequate LNH in colorectal cancer, so PCT is needed for adequate LNH in these patients.

Verified
Journal Article
Open access
PDF file
SHSung Yong Han
Sung Yong Han
DKDong Uk Kim
Dong Uk Kim
HNHyeong-seok Nam
Hyeong-seok Nam
DKDae-Hwan Kang
Dae-Hwan Kang
SJSung Ill Jang
Sung Ill Jang
JCJae Hee Cho
Jae Hee Cho
Background: Intraductal papillary neoplasm of the bile duct (IPNB) is a precancerous lesion of cholangiocarcinoma, for which surgical resection is the most effective treatment. We evaluated the predictors of malignancy in IPNB according to anatomical location and the prognosis without surgery. Methods: A total of 196 IPNB patients who underwent pathologic confirmation by surgical resection or endoscopic retrograde cholangiography or percutaneous transhepatic cholangioscopic biopsy were included. Clinicopathological findings of IPNB with invasive carcinoma or mucosal dysplasia were analyzed according to anatomical location. Results: Of the 116 patients with intrahepatic IPNB (I-IPNB) and 80 patients with extrahepatic IPNB (E-IPNB), 62 (53.4%) and 61 (76.3%) were diagnosed with invasive carcinoma, respectively. Multivariate analysis revealed that mural nodule > 12 mm (p = 0.043) in I-IPNB and enhancement of mural nodule (p = 0.044) in E-IPNB were predictive factors for malignancy. For pathologic discrepancy before and after surgery, IPNB has a 71.2% sensitivity and 82.3% specificity. In the non-surgical IPNB group, composed of nine I-IPNB and seven E-IPNB patients, 43.7% progressed to IPNB with invasive carcinoma within 876 days. Conclusions: E-IPNB has a higher rate of malignancy than I-IPNB. The predictive factor for malignancy is mural nodule > 12 mm in I-IPNB and mural nodule enhancement in E-IPNB.

16 July 2018 in Scandinavian Journal of Gastroenterology
Verified
Journal Article
Closed access
HNHyeong-seok Nam
Hyeong-seok Nam
CCCheol Woong Choi
Cheol Woong Choi
SKSu Jin Kim
Su Jin Kim
DKDae-Hwan Kang
Dae-Hwan Kang
HKHyung Wook Kim
Hyung Wook Kim
DRDaeGon Ryu
DaeGon Ryu
Objective: Endoscopic submucosal dissection (ESD) has been accepted as the treatment of choice for gastric epithelial neoplasia. Endoscopic characteristics of the primary lesion and post-ESD scars may be informative to predict the possibility of local recurrence. Methods: Between November 2008 and July 2015, a retrospective study was conducted in a single-tertiary referral hospital. Consecutive patients who underwent ESD for early gastric cancer (EGC) or high-grade dysplasia were analyzed to evaluate the incidence of local recurrence and associated endoscopic characteristics. Results: A total of 639 lesions were analyzed. The rates of en-bloc and complete resection were 98.1% and 95.5%, respectively. A total of 15 local recurrent lesions were found (2.3%). The endoscopic findings of primary lesions associated with local recurrence were a lesion size ≥20 mm (odds ratio, OR, 4.408; 95% confidence interval, CI, 1.369–14.186, p = .013) and incomplete endoscopic resection (OR 17.059, 95% CI 4.887–59.551, p < .001). During follow-up endoscopic examinations, atypical scar findings (non-flat morphology, erythematous color change and uneven surface pattern) were significant endoscopic findings to predict local recurrence. Local recurrence was absent for ESD scars with even-flat morphology without erythema. Conclusion: Lesions with larger size (≥ 20 mm) and incompletely resected lesions had higher risk of local recurrence. Endoscopic forceps biopsy is unnecessary for even-flat ESD scar without erythematous changes.

1 December 2017 in Medicine
Verified
Journal Article
Open access
JHJoung Boom Hong
Joung Boom Hong
DKDae Hwan Kang
Dae Hwan Kang
HNHyeong-seok Nam
Hyeong-seok Nam
CCCheol Woong Choi
Cheol Woong Choi
HKHyung Wook Kim
Hyung Wook Kim
WCWoo Hyeok Choi
Woo Hyeok Choi
Endoscopic bilateral stenting has been increasingly performed for advanced hilar obstruction. As disease progresses, stent malfunction eventually occurs. However, endoscopic reintervention is difficult in these patients. We aimed to evaluate a suitable reintervention procedure for stent malfunction after stent-in-stent (SIS) deployment for malignant hilar obstruction. Among 52 patients with bilateral stenting performed using the SIS method between September 2009 and June 2016, 20 patients with stent malfunction were enrolled in this study. Reintervention was performed endoscopically or percutaneously. Technical and functional success rates were evaluated retrospectively. Technical and functional success rates of endoscopic reintervention were 83% (10/12) and 80% (8/10), respectively. Endoscopic bilateral and unilateral reintervention success rates were 75% (6/8) and 100% (4/4), respectively. For bilateral reintervention, either plastic or plastic and metal stents were used. Endoscopic reintervention could be considered for in-stent malfunction if patients are in fair condition after SIS placement for malignant hilar obstruction. Decisions regarding whether to use bilateral or unilateral drainage and the type of stent to use should depend on the conditions of the disease and the patient.

16 September 2022 in Medicine
Verified
Journal Article
Open access
DRDaeGon Ryu
DaeGon Ryu
SKSu Jin Kim
Su Jin Kim
CCCheol Woong Choi
Cheol Woong Choi
DKDae-Hwan Kang
Dae-Hwan Kang
HKHyung Wook Kim
Hyung Wook Kim
SHSun Hwi Hwang
Sun Hwi Hwang
The management of gastroduodenal neuroendocrine tumor (NET) has been controversial between radical surgical resection and local excision including endoscopic resection. A gastroduodenal NET grade (G), measured by their mitotic rate and Ki67 proliferation index, is important to predict prognosis. In this study, we aimed to compare the clinical outcomes of gastroduodenal NET according to grades in order to identify poor prognostic factors of gastroduodenal NETs. Fifty-four gastroduodenal NETs diagnosed between December 2008 and December 2020 in a tertiary referral hospital were retrospectively reviewed. The clinical outcomes of gastroduodenal NETs, according to tumor grades and factors associated with NET G2-3, were analyzed. A total of 52 gastroduodenal NET patients was enrolled. The mean follow-up period was 56.2 ± 40.1 months. The mean size of gastric and duodenal NET was 7.9 ± 11.0 mm and 9.8 ± 7.6 mm, respectively. During the study period, 72.7% (16/22) of gastric NETs and 83.3% (25/30) of duodenal NETS were G1. All G1 gastroduodenal NETs showed no lymph node or distant metastasis during the study periods. All G3 gastroduodenal NETs showed metastasis (one lymph node metastasis and 3 hepatic metastases). Among metastatic NETs, the smallest tumor size was a 13 mm gastric G3 NET. Factors associated with G2-3 NETs were larger tumor size, mucosal ulceration, proper muscle or deeper invasion, and lymphovascular invasion. A small-sized gastroduodenal NET confined to submucosa without surface ulceration may be suitable for endoscopic resection. After local resection of a gastroduodenal NET (G1) without lymphovascular and muscle proper invasion, follow-up examination without radical surgical resection can be recommended. G3 NETs may be treated by radical surgical resection, regardless of tumor size.