Byung Kyu Ahn
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Byung Kyu Ahn has a total of 52 co-authors. Here are the top co-authors by number of shared publications:
Kang Hong Lee
Department of Surgery, College of Medicine, Hanyang University
4 shared publications- Kang Hong Lee
Department of Surgery, College of Medicine, Hanyang University, Seoul, Republic of Korea
4 shared publications Seung Sam Paik
Department of Pathology, College of Medicine, Hanyang University
3 shared publicationsC.M. Kang
2 shared publicationsBo-Kyeong Kang
Department of Radiology, Hanyang University College of Medicine, Seoul, South Korea
1 shared publication- Dong Soo Han
Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Korea
1 shared publication
Latest Publications
- 30 April 2026
- Published by Oxford University Press (OUP) in Inflammatory Bowel Diseases
- Vol. 32 (9) , 1760-1769
Extraintestinal manifestations in Korean patients with inflammatory bowel disease: A nationwide population-based study from 2005 to 2017
Background: Extraintestinal manifestations (EIMs) significantly contribute to morbidity in individuals with inflammatory bowel disease (IBD); however, population-based East Asian data remain limited. We evaluated EIM burden in a nationwide Korean IBD cohort. Methods: This nationwide retrospective cohort study was conducted using data from the Korean National Health Insurance Service between 2005 and 2017. Individuals with ulcerative colitis (UC) or Crohn’s disease (CD) were identified using the International Classification of Diseases–10th Edition and rare intractable disease codes. EIM incidence, associated risk factors, interval from IBD diagnosis to EIM onset, and trends by sex and age were examined. Results: Among 69 414 individuals with IBD (48 689 UC, 20 725 CD), 42.23% developed at least 1 EIM. Dermatologic manifestations were the most common (17.02%), followed by musculoskeletal (16.36%), hepatopancreaticobiliary (15.48%), and ophthalmologic (7.83%) manifestations. Low socioeconomic status, smoking history, female sex, and higher Charlson Comorbidity Index scores independently correlated with EIM development in UC (hazard ratios of 2.14, 1.18, 1.15, and 1.08, respectively) and CD (hazard ratios of 1.98, 1.20, 1.18, and 1.09, respectively). Most EIMs developed within 4 to 6 years postdiagnosis, with musculoskeletal EIMs occurring earliest (median 42.9 months [interquartile range: 10.3-89.5 months]). Annual EIM incidence increased steadily over time across all age groups. Conclusions: EIMs affected 42.23% of Korean individuals with IBD, most frequently appearing 4 to 6 years postdiagnosis. Low socioeconomic status, smoking history, female sex, and higher Charlson Comorbidity Index scores consistently correlated with EIM occurrence, and incidence increased steadily over time, highlighting the need for sustained, personalized monitoring and timely intervention.
- 30 April 2026
- Published by Oxford University Press (OUP) in Inflammatory Bowel Diseases
- Vol. 32 (9) , 1760-1769
Extraintestinal manifestations in Korean patients with inflammatory bowel disease: A nationwide population-based study from 2005 to 2017
Background: Extraintestinal manifestations (EIMs) significantly contribute to morbidity in individuals with inflammatory bowel disease (IBD); however, population-based East Asian data remain limited. We evaluated EIM burden in a nationwide Korean IBD cohort. Methods: This nationwide retrospective cohort study was conducted using data from the Korean National Health Insurance Service between 2005 and 2017. Individuals with ulcerative colitis (UC) or Crohn’s disease (CD) were identified using the International Classification of Diseases–10th Edition and rare intractable disease codes. EIM incidence, associated risk factors, interval from IBD diagnosis to EIM onset, and trends by sex and age were examined. Results: Among 69 414 individuals with IBD (48 689 UC, 20 725 CD), 42.23% developed at least 1 EIM. Dermatologic manifestations were the most common (17.02%), followed by musculoskeletal (16.36%), hepatopancreaticobiliary (15.48%), and ophthalmologic (7.83%) manifestations. Low socioeconomic status, smoking history, female sex, and higher Charlson Comorbidity Index scores independently correlated with EIM development in UC (hazard ratios of 2.14, 1.18, 1.15, and 1.08, respectively) and CD (hazard ratios of 1.98, 1.20, 1.18, and 1.09, respectively). Most EIMs developed within 4 to 6 years postdiagnosis, with musculoskeletal EIMs occurring earliest (median 42.9 months [interquartile range: 10.3-89.5 months]). Annual EIM incidence increased steadily over time across all age groups. Conclusions: EIMs affected 42.23% of Korean individuals with IBD, most frequently appearing 4 to 6 years postdiagnosis. Low socioeconomic status, smoking history, female sex, and higher Charlson Comorbidity Index scores consistently correlated with EIM occurrence, and incidence increased steadily over time, highlighting the need for sustained, personalized monitoring and timely intervention.
- Open Access
- 18 February 2026
- Published by Elsevier in Current Problems in Surgery
- Vol. 77, 102008
Absence of AMPK expression is an independent risk factor for stage II/III colorectal cancer recurrence
- 18 February 2026
- Published by Elsevier in Current Problems in Surgery
- Vol. 77, 102008
Open AccessAbsence of AMPK expression is an independent risk factor for stage II/III colorectal cancer recurrence
- Open Access
- 16 March 2023
- Published by MDPI AG in Diagnostics
- Vol. 13 (6) , 1140
Low MTUS1 Protein Expression Is Associated with Poor Survival in Patients with Colorectal Adenocarcinoma
Introduction: Microtubule-associated tumor suppressor 1 (MTUS1) is a novel tumor suppressor protein involved in cell proliferation, migration, and tumor growth. MTUS1 is thought to be downregulated in various human cancers and associated with poor prognosis. We evaluated the clinicopathologic significance and prognostic value of MTUS1 in colorectal adenocarcinoma. Methods: Immunohistochemical staining for MTUS1 was performed on tissue microarrays of 393 colorectal adenocarcinoma cases, and MTUS1 staining was classified into high- and low-expression groups. Then, we investigated the correlations between MTUS1 protein expression and various clinicopathological parameters and patient survival. Results: MTUS1 protein was expressed at various grade levels in the cytoplasm of tumor cells, which showed loss or decreased expression of MTUS1. A total of 253 cases (64.4%) were classified into the low MTUS1 protein expression group and 140 cases (35.6%) into the high MTUS1 expression group. A low level of MTUS1 protein significantly correlated with tumor size (p = 0.047), histological grade (p < 0.001), lymphovascular invasion (p < 0.001), perineural invasion (p = 0.047), and lymph node metastasis (p < 0.001). Survival analyses showed that patients with low MTUS1 protein expression had worse overall survival (p = 0.007, log-rank test) and worse recurrence-free survival (p = 0.019, log-rank test) than those with high MTUS1 expression. Conclusions: Low MTUS1 protein expression is associated with adverse clinicopathological characteristics and poor survival outcomes in patients with colorectal adenocarcinoma. These results suggest that MTUS1 functions as a tumor suppressor in colorectal adenocarcinoma and could be a potential prognostic biomarker.
- 16 March 2023
- Published by MDPI AG in Diagnostics
- Vol. 13 (6) , 1140
Open AccessLow MTUS1 Protein Expression Is Associated with Poor Survival in Patients with Colorectal Adenocarcinoma
Introduction: Microtubule-associated tumor suppressor 1 (MTUS1) is a novel tumor suppressor protein involved in cell proliferation, migration, and tumor growth. MTUS1 is thought to be downregulated in various human cancers and associated with poor prognosis. We evaluated the clinicopathologic significance and prognostic value of MTUS1 in colorectal adenocarcinoma. Methods: Immunohistochemical staining for MTUS1 was performed on tissue microarrays of 393 colorectal adenocarcinoma cases, and MTUS1 staining was classified into high- and low-expression groups. Then, we investigated the correlations between MTUS1 protein expression and various clinicopathological parameters and patient survival. Results: MTUS1 protein was expressed at various grade levels in the cytoplasm of tumor cells, which showed loss or decreased expression of MTUS1. A total of 253 cases (64.4%) were classified into the low MTUS1 protein expression group and 140 cases (35.6%) into the high MTUS1 expression group. A low level of MTUS1 protein significantly correlated with tumor size (p = 0.047), histological grade (p < 0.001), lymphovascular invasion (p < 0.001), perineural invasion (p = 0.047), and lymph node metastasis (p < 0.001). Survival analyses showed that patients with low MTUS1 protein expression had worse overall survival (p = 0.007, log-rank test) and worse recurrence-free survival (p = 0.019, log-rank test) than those with high MTUS1 expression. Conclusions: Low MTUS1 protein expression is associated with adverse clinicopathological characteristics and poor survival outcomes in patients with colorectal adenocarcinoma. These results suggest that MTUS1 functions as a tumor suppressor in colorectal adenocarcinoma and could be a potential prognostic biomarker.
- Open Access
- 1 January 2022
- Published by Elsevier in Asian Journal of Surgery
- Vol. 45 (1) , 353-359
Socio-demographic factors and lifestyle associated with symptomatic hemorrhoids: Big data analysis using the National Health insurance Service-National Health screening cohort (NHIS-HEALS) database in Korea
- 1 January 2022
- Published by Elsevier in Asian Journal of Surgery
- Vol. 45 (1) , 353-359
Open AccessSocio-demographic factors and lifestyle associated with symptomatic hemorrhoids: Big data analysis using the National Health insurance Service-National Health screening cohort (NHIS-HEALS) database in Korea
- 7 January 2019
- Published by Taylor & Francis in Acta Chirurgica Belgica
- Vol. 119 (6) , 384-389
The usefulness of the status of extranodal tumor extension as a factor that can predict the recurrence of stage III colorectal cancer
Background: Extranodal tumor extension (ENTE) is considered a poor prognostic factor in colorectal cancer (CRC). This study aimed to investigate the risk factors for recurrence according to ENTE status in stage III CRC. Methods: We retrospectively evaluated 169 consecutive stage III CRC patients. All patients underwent a curative resection between 2005 and 2010. The presence or absence of ENTE was assessed in the resected lymph nodes. Results: ENTE was observed in 65 (38.5%). Recurrence occurred in 38 patients (22.5%) and was more frequent (p = .041) in the ENTE (+) group. Disease-free survival (p = .016) was significantly shorter in the ENTE (+) group than in the ENTE (−) group. In a univariable analysis, recurrence was associated with vascular invasion (p = .006), perforation (p = .024) in the ENTE (−) group and perforation (p = .048) in the ENTE (+) group. In a Cox’s regression test, vascular invasion (p = .014) and the higher ratio of metastatic lymph nodes/total removed lymph nodes (MLN/TLN) (0.009) in the ENTE (−) group and perforation (p = .025) in the ENTE (+) group were independent risk factors of recurrence. Conclusions: Vascular invasion and the higher ratio of MLN/TLN in ENTE (−) patients and perforation in ENTE (+) patients were independent risk factors of recurrence.
- 7 January 2019
- Published by Taylor & Francis in Acta Chirurgica Belgica
- Vol. 119 (6) , 384-389
The usefulness of the status of extranodal tumor extension as a factor that can predict the recurrence of stage III colorectal cancer
Background: Extranodal tumor extension (ENTE) is considered a poor prognostic factor in colorectal cancer (CRC). This study aimed to investigate the risk factors for recurrence according to ENTE status in stage III CRC. Methods: We retrospectively evaluated 169 consecutive stage III CRC patients. All patients underwent a curative resection between 2005 and 2010. The presence or absence of ENTE was assessed in the resected lymph nodes. Results: ENTE was observed in 65 (38.5%). Recurrence occurred in 38 patients (22.5%) and was more frequent (p = .041) in the ENTE (+) group. Disease-free survival (p = .016) was significantly shorter in the ENTE (+) group than in the ENTE (−) group. In a univariable analysis, recurrence was associated with vascular invasion (p = .006), perforation (p = .024) in the ENTE (−) group and perforation (p = .048) in the ENTE (+) group. In a Cox’s regression test, vascular invasion (p = .014) and the higher ratio of metastatic lymph nodes/total removed lymph nodes (MLN/TLN) (0.009) in the ENTE (−) group and perforation (p = .025) in the ENTE (+) group were independent risk factors of recurrence. Conclusions: Vascular invasion and the higher ratio of MLN/TLN in ENTE (−) patients and perforation in ENTE (+) patients were independent risk factors of recurrence.
- 30 April 2018
- Published by Springer Nature in International Journal of Colorectal Disease
- Vol. 33 (9) , 1303-1307
Higher visceral fat area/subcutaneous fat area ratio measured by computed tomography is associated with recurrence and poor survival in patients with mid and low rectal cancers
Obesity is thought to influence postoperative complications and recurrence of mid and low rectal cancer (MLRC) because of intraoperative technical difficulties. However, few reports have described the relationship between obesity indices and the clinical outcomes of MLRC. This study aimed to investigate the association between visceral obesity on computed tomography (CT) and oncolofical outcomes after surgery for MLRC and identify the obesity index that most accurately reflects clinical outcomes.
- 30 April 2018
- Published by Springer Nature in International Journal of Colorectal Disease
- Vol. 33 (9) , 1303-1307
Higher visceral fat area/subcutaneous fat area ratio measured by computed tomography is associated with recurrence and poor survival in patients with mid and low rectal cancers
Obesity is thought to influence postoperative complications and recurrence of mid and low rectal cancer (MLRC) because of intraoperative technical difficulties. However, few reports have described the relationship between obesity indices and the clinical outcomes of MLRC. This study aimed to investigate the association between visceral obesity on computed tomography (CT) and oncolofical outcomes after surgery for MLRC and identify the obesity index that most accurately reflects clinical outcomes.
- 2 August 2016
- Published by Springer Nature in Langenbeck's Archives of Surgery
- Vol. 401 (8) , 1203-1210
Loss of APAF-1 expression is associated with early recurrence in stage I, II, and III colorectal cancer
Purpose Apoptotic protease activating factor-1 (APAF-1) is a key regulator in the mitochondrial apoptotic pathway and an important diagnostic and therapeutic biomarker. Loss of APAF-1 expression has been observed in various tumors including colorectal cancer. The aim of our study was to evaluate the relationship between loss of APAF-1 expression and early recurrence of stage I–III colorectal cancer. Methods We investigated 165 out of 492 patients who had undergone curative resection for colorectal cancer between 1991 and 2001. Sixty-one patients (37.0 %) had early recurrence within 1 year after surgery. Tissue microarrays were used for immunohistochemical detection of APAF-1. Results The mean age of patients with recurrence was 58 years (range, 24–85); 88 (53.3 %, 88/165) were male. APAF-1 was expressed in 32 (19.4 %, 32/165) cases and was not expressed in 133 (80.6 %, 133/165). In univariate analysis, early recurrence significantly correlated with loss of APAF-1 expression (p = 0.017), tumor stage (p = 0.005), N category (p = 0.001), and lymphatic invasion (p = 0.008). In a logistic regression model, loss of APAF-1 expression (p = 0.015, 95 % CI = 1.280–10.063) and N category (p = 0.001, 95 % CI = 0.004–0.739) proved to be independent risk factors associated with early recurrence. In patients with lymph node metastasis, early recurrence was more frequent in the APAF-1-negative group than in the APAF-1-positive group (46.2 % (54/117) vs. 22.2 % (6/27), p = 0.023). Conclusions Loss of APAF-1 expression is associated with early recurrence in stage I–III colorectal cancer, suggesting that APAF-1 may have clinical value as a predictive marker of early recurrence.
- 2 August 2016
- Published by Springer Nature in Langenbeck's Archives of Surgery
- Vol. 401 (8) , 1203-1210
Loss of APAF-1 expression is associated with early recurrence in stage I, II, and III colorectal cancer
Purpose Apoptotic protease activating factor-1 (APAF-1) is a key regulator in the mitochondrial apoptotic pathway and an important diagnostic and therapeutic biomarker. Loss of APAF-1 expression has been observed in various tumors including colorectal cancer. The aim of our study was to evaluate the relationship between loss of APAF-1 expression and early recurrence of stage I–III colorectal cancer. Methods We investigated 165 out of 492 patients who had undergone curative resection for colorectal cancer between 1991 and 2001. Sixty-one patients (37.0 %) had early recurrence within 1 year after surgery. Tissue microarrays were used for immunohistochemical detection of APAF-1. Results The mean age of patients with recurrence was 58 years (range, 24–85); 88 (53.3 %, 88/165) were male. APAF-1 was expressed in 32 (19.4 %, 32/165) cases and was not expressed in 133 (80.6 %, 133/165). In univariate analysis, early recurrence significantly correlated with loss of APAF-1 expression (p = 0.017), tumor stage (p = 0.005), N category (p = 0.001), and lymphatic invasion (p = 0.008). In a logistic regression model, loss of APAF-1 expression (p = 0.015, 95 % CI = 1.280–10.063) and N category (p = 0.001, 95 % CI = 0.004–0.739) proved to be independent risk factors associated with early recurrence. In patients with lymph node metastasis, early recurrence was more frequent in the APAF-1-negative group than in the APAF-1-positive group (46.2 % (54/117) vs. 22.2 % (6/27), p = 0.023). Conclusions Loss of APAF-1 expression is associated with early recurrence in stage I–III colorectal cancer, suggesting that APAF-1 may have clinical value as a predictive marker of early recurrence.
- Open Access
- 28 March 2015
- Published by Springer Nature in BMC Neurology
- Vol. 15 (1) , 1-5
Chronic inflammatory demyelinating polyneuropathy-like neuropathy as an initial presentation of Crohn’s disease
Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare complication of Crohn's disease (CD), and it is uncertain whether it is associated with CD itself or with its treatment. We describe a case of CIDP-like neuropathy as an initial symptom of CD. The neurologic symptoms of the patient which responded partially to intravenous immunoglobulin (IVIG) recovered after resection of the appendiceal CD. A 17-year-old male had experienced three separate attacks of motor weakness and paresthesia of all four extremities over a period of 7 months. The electrophysiologic findings revealed a demyelinating sensory-motor polyneuropathy which was compatible with CIDP. However, repeated intravenous IVIG (2 g/kg) treatment gave only a partial response. Four days after the last discharge, he was diagnosed as appendiceal CD after surgical resection of a periappendiceal abscess. His neurologic symptoms and electrophysiologic findings recovered without any maintenance therapy. CIDP-like neuropathy can be an initial presentation of CD, and recovery of the CIDP symptoms may result from resection of the CD. Clinicians should be aware of the possibility of CD in patients with intractable CIDP symptoms.
- 28 March 2015
- Published by Springer Nature in BMC Neurology
- Vol. 15 (1) , 1-5
Open AccessChronic inflammatory demyelinating polyneuropathy-like neuropathy as an initial presentation of Crohn’s disease
Chronic inflammatory demyelinating polyneuropathy (CIDP) is a rare complication of Crohn's disease (CD), and it is uncertain whether it is associated with CD itself or with its treatment. We describe a case of CIDP-like neuropathy as an initial symptom of CD. The neurologic symptoms of the patient which responded partially to intravenous immunoglobulin (IVIG) recovered after resection of the appendiceal CD. A 17-year-old male had experienced three separate attacks of motor weakness and paresthesia of all four extremities over a period of 7 months. The electrophysiologic findings revealed a demyelinating sensory-motor polyneuropathy which was compatible with CIDP. However, repeated intravenous IVIG (2 g/kg) treatment gave only a partial response. Four days after the last discharge, he was diagnosed as appendiceal CD after surgical resection of a periappendiceal abscess. His neurologic symptoms and electrophysiologic findings recovered without any maintenance therapy. CIDP-like neuropathy can be an initial presentation of CD, and recovery of the CIDP symptoms may result from resection of the CD. Clinicians should be aware of the possibility of CD in patients with intractable CIDP symptoms.
- 4 May 2013
- Published by Springer Nature in Surgical Endoscopy
- Vol. 27 (10) , 3776-3780
What is the optimal time for laparoscopic cholecystectomy in gallbladder empyema?
With the accumulating experience in laparoscopic surgery, early laparoscopic cholecystectomy (LC) is increasingly offered for acute cholecystitis. However, early LC without percutaneous transhepatic gallbladder drainage (PTGBD) for gallbladder empyema is still believed to be unsafe. The purpose of this study was to determine the optimal time for LC in gallbladder empyema. A retrospective analysis was carried out of patients who underwent LC without PTGBD for gallbladder empyema between August 2007 and December 2010. All cases were confirmed by biopsy. The patients were divided into two groups on the basis of a cutoff of 72 h. LC for gallbladder empyema was performed without PTGBD in 61 patients during the study period. The overall conversion rate was 6.6 %. Based on the 72 h cutoff, there were 33 patients in the early group and 28 in the delayed group. There were no significant differences between early and late patients with respect to operation duration (75.5 vs. 71.4 min, p = 0.537), postoperative hospital stay (4.2 vs. 3.3 days, p = 0.109), conversion rate (12.1 vs. 0 %, p = 0.118), and complication rate (12.1 vs. 3.6 %, p = 0.363). However, the early group had a significantly shorter total hospital stay (5.3 vs. 8.7 days, p = 0.001). Early LC without PTGBD is safe and feasible for gallbladder empyema and is associated with a low conversion rate. Delayed LC for gallbladder empyema has no advantages and results in longer total hospital stays. LC should be performed as soon as possible within 72 h after admission to decrease length of hospital stay.
- 4 May 2013
- Published by Springer Nature in Surgical Endoscopy
- Vol. 27 (10) , 3776-3780
What is the optimal time for laparoscopic cholecystectomy in gallbladder empyema?
With the accumulating experience in laparoscopic surgery, early laparoscopic cholecystectomy (LC) is increasingly offered for acute cholecystitis. However, early LC without percutaneous transhepatic gallbladder drainage (PTGBD) for gallbladder empyema is still believed to be unsafe. The purpose of this study was to determine the optimal time for LC in gallbladder empyema. A retrospective analysis was carried out of patients who underwent LC without PTGBD for gallbladder empyema between August 2007 and December 2010. All cases were confirmed by biopsy. The patients were divided into two groups on the basis of a cutoff of 72 h. LC for gallbladder empyema was performed without PTGBD in 61 patients during the study period. The overall conversion rate was 6.6 %. Based on the 72 h cutoff, there were 33 patients in the early group and 28 in the delayed group. There were no significant differences between early and late patients with respect to operation duration (75.5 vs. 71.4 min, p = 0.537), postoperative hospital stay (4.2 vs. 3.3 days, p = 0.109), conversion rate (12.1 vs. 0 %, p = 0.118), and complication rate (12.1 vs. 3.6 %, p = 0.363). However, the early group had a significantly shorter total hospital stay (5.3 vs. 8.7 days, p = 0.001). Early LC without PTGBD is safe and feasible for gallbladder empyema and is associated with a low conversion rate. Delayed LC for gallbladder empyema has no advantages and results in longer total hospital stays. LC should be performed as soon as possible within 72 h after admission to decrease length of hospital stay.
- Open Access
- 1 May 2013
- Published by SAGE Publications in The American Surgeon™
- Vol. 79 (5) , 544-547
Characteristics and Prognoses of Small Obstructing Colorectal Cancers: The Combination of Gross Findings Has Value in Predicting Recurrence after Curative Therapy
- 1 May 2013
- Published by SAGE Publications in The American Surgeon™
- Vol. 79 (5) , 544-547
Open AccessCharacteristics and Prognoses of Small Obstructing Colorectal Cancers: The Combination of Gross Findings Has Value in Predicting Recurrence after Curative Therapy