Jeong Sik Byeon

Risk Factors for Immediate Postpolypectomy Bleeding of the Colon: A Multicenter Study

OBJECTIVES:The aims of this prospective study were to document the incidence of colon immediate postpolypectomy bleeding (IPPB) according to grade, and to identify potential risk factors of IPPB in patients who have received complete colonoscopy and polypectomy because of a colorectal polyp.METHODS:This was a prospective, cross-sectional study of 5,152 patients treated at 11 tertiary medical centers between July 2003 and July 2004. Patient-related, polyp-related, and procedure-related variables were evaluated as potential risk factors for IPPB. IPPB was defined as a bleeding occurring during the procedure and was graded as G1–G4. Risk factors associated with IPPB were analyzed by univariate and multivariate logistic regression analysis.RESULTS:A total of 9,336 colonic polyps were removed in 5,152 patients, and 262 (2.8%) colorectal polyps in 215 patients presented with IPPB. Polyp-based multivariate analysis revealed that old age (≥65 yr), comorbid cardiovascular or chronic renal disease, anticoagulant use, polyp size greater than 1 cm, gross morphology of polyps such as pedunculated polyp or laterally spreading tumor, poorer bowel preparation, cutting mode of the electrosurgical current, and the inadvertent cutting of a polyp before current application were significant risk factors for IPPB.CONCLUSION:Nine factors have been found to be associated with IPPB and polypectomy should be undertaken with caution under these conditions.

The Asia-Pacific Colorectal Screening score: a validated tool that stratifies risk for colorectal advanced neoplasia in asymptomatic Asian subjects

Objective To develop and validate a clinical risk score predictive of risk for colorectal advanced neoplasia for Asia. Methods A prospective, cross-sectional and multicentre study was carried out in tertiary hospitals in 11 Asian cities. The subjects comprise 2752 asymptomatic patients undergoing screening colonoscopy. From a development set of 860 asymptomatic subjects undergoing screening colonoscopy, multiple logistic regression was applied to identify significant risk factors for advanced colorectal neoplasia defined as invasive carcinoma or advanced adenoma. The ORs for significant risk factors were utilised to develop a risk score ranging from 0 to 7 (Asia-Pacific Colorectal Screening (APCS) score). Three tiers of risk were arbitrarily defined: 0–1 ‘average risk’ (AR); 2–3 ‘moderate risk’ (MR); and 4–7 ‘high risk’ (HR). Subjects undergoing screening colonoscopy between July 2006 and December 2007 were prospectively enrolled to form an independent validation group. Each subject had a personal APCS score calculated by summing the points attributed from the presence of risk factors in the individuals. The performance of the APCS score in predicting risk of advanced neoplasia was evaluated. Results There were 860 subjects in the derivation set and 1892 subjects in the validation set, with a baseline prevalence of advanced neoplasia of 4.5% and 3%, respectively. Applying the APCS stratification in the validation set, 559 subjects (29.5%) were in the AR tier, 966 subjects (51.1%) in the MR tier and 367 (19.4%) subjects in the HR tier. The prevalence of advanced neoplasia in the AR, MR and HR groups was 1.3, 3.2 and 5.2%, respectively. The subjects in the MR and HR tiers had 2.6-fold (95% CI 1.1 to 6.0) and 4.3-fold (95% CI 1.8 to 10.3) increased prevalence of advanced neoplasia, respectively, than those in the AR tier. Conclusions The APCS score based on age, gender, family history and smoking is useful in selecting asymptomatic Asian subjects for priority of colorectal screening.

An adequate level of training for technical competence in screening and diagnostic colonoscopy: a prospective multicenter evaluation of the learning curve

BACKGROUND Various training programs in colonoscopy recommend that trainees should perform at least 100 to 200 procedures to be considered technically competent at diagnostic colonoscopy. OBJECTIVE Our purpose was to determine the adequate level of training for technical competence in screening and diagnostic colonoscopy. DESIGN A prospective multicenter trial. SETTING Fifteen tertiary care academic medical centers. PATIENTS Over 8 months we prospectively evaluated the procedures of 24 first-year GI fellows in 15 tertiary care academic medical centers. A total of 4351 colonoscopies were assessed prospectively with variable clinical factors. INTERVENTION Cecal intubation was documented by photographing the identified cecal landmarks, including the appendiceal orifice and the ileocecal valve. MAIN OUTCOME MEASUREMENTS Acquisition of competence (success rate) was evaluated for colonoscopic training on the basis of 2 objective criteria: (1) adjusted completion rate (>90%) and (2) cecal intubation time (<20 minutes). RESULTS The overall success rate was 83.5% (3635/4351). The mean cecal intubation time was 9.23 +/- 4.63 minutes. The success rate significantly improved and reached the requisite standard of competence after 150 procedures (71.5%, 82.6%, 91.3%, 94.4%, 98.4%, and 98.7%, respectively, for every 50 consecutive blocks). The polyp detection rate did not improve significantly during the 8 months and was not correlated with the learning curve. In addition, mean time to cecal intubation decreased significantly, from 11.16 to 8.39 minutes, after 150 procedures. Logistic regression analysis found that prolonged cecal intubation was caused by the following factors: elderly patients, female sex, low body mass index, poor bowel preparation, poor American Society of Anesthesiologists status, abdominal pain as an indication, instructors supervision, and low case volume. LIMITATIONS We did not record final pathologic reports of detected polyps and withdrawal time. CONCLUSIONS Competence in technically efficient screening and diagnostic colonoscopy generally requires experience with more than 150 cases. Also, factors associated with prolonged cecal intubation for typical trainees did not differ from those for experienced colonoscopists.

Efficacy of prepackaged, low residual test meals with 4L polyethylene glycol versus a clear liquid diet with 4L polyethylene glycol bowel preparation: a randomized trial.

Background and study aims:  A prepackaged low residue one‐day diet (breakfast, lunch and dinner) has been recently developed to improve patient tolerance for bowel preparation prior to colonoscopy. The aims of this study were to evaluate the efficacy and tolerability of bowel preparation protocols based on a low residue diet and 4L polyethylene glycol (PEG) solution, and to compare these new options with the traditional liquid diet and the PEG 4L lavage.

Influences of thiopurine methyltransferase genotype and activity on thiopurine-induced leukopenia in Korean patients with inflammatory bowel disease: a retrospective cohort study.

Background and Aim Myelotoxicity has been shown to be very common in Korean patients with inflammatory bowel disease (IBD) during azathioprine (AZA) or 6-mercaptopurine (6–MP) treatment. The purpose of this study was to investigate the relative risk of the thiopurine methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) genotypes and TPMT activity for the development of leukopenia in Korean IBD patients during AZA/6-MP treatment. Methods We retrospectively analyzed 286 Korean patients with IBD who had been treated with AZA/6-MP for at least 6 months between June 1996 and September 2006. Common TPMT mutations, including TPMT*1, *2, *3A, *3B, and *3C, and ITPA mutations, including 94C>A and IVS2+21A>C, were determined using a high-performance liquid chromatography method. TPMT activity was measured using liquid chromatography with coupled mass spectrometry/mass spectrometry. Results Leukopenia occurred in 118 cases (41.3%). TPMT *1/*3C was detected in 7 cases (2.4%), and ITPA 94 C>A was detected in 66 cases (23.1%), including 63 heterozygotes (22.1%) and 3 homozygotes (1.0%). The median TPMT activity was 9.3 U/mL (interquartile range 10.4, range 2.1 to 76.2). Cox regression analysis revealed that patients with heterozygous *3C type TPMT had a higher probability of leukopenia than those with wild type TPMT (P=0.02). Patients with intermediate TPMT activity had a lower probability of leukopenia than those with low activity (P=0.01). However, the ITPA genotype did not affect the risk of leukopenia. Conclusions Our data showed that it could be helpful to examine TPMT genotypes and to measure TPMT activity in Korean patients taking AZA/6-MP to predict the development of leukopenia.

Comparison of a newly designed double-layered combination covered stent and D-weave uncovered stent for decompression of obstructive colorectal cancer: a prospective multicenter study.

PURPOSE: Stent reocclusion and migration are the most important complications after stent insertion. To overcome both problems, a double-layered combination covered stent was developed. Our purpose was to compare the efficacy and safety of the newly designed double-layered combination covered stent (Niti-S enteral colonic stent, Comvi type) and the double-wire woven uncovered stent (Niti-S enteral colonic stent, D-type) in the treatment of malignant colorectal obstructions. METHODS: Sixty-eight patients with obstructive colorectal cancer underwent stent placement for preoperative decompression (n = 30) or palliative purpose (n = 38) at 6 medical centers. Combination covered stents were used in 31 patients and uncovered stents were used in 37 patients. RESULTS: There were no significant differences between both stents in terms of technical and clinical success rates. Regarding complications after stent insertion, there was no significant difference in early stent occlusion and migration rate between the combination covered stents and the uncovered stents. Despite a trend toward lower rates of late stent occlusion in the combination covered stent group, there was no significant difference in the rate of late stent occlusion by tumor ingrowth between the 2 groups (0% vs 20%, respectively; P = .107), and late stent migration occurred significantly more often with the combination covered stent (22.2% vs 0%, respectively; P = .041). However, we observed no significant difference in the overall late-complication rates and stent patency duration between the 2 groups. CONCLUSIONS: In our study, we could not prove that the newly designed double-layered combination covered stents have preventive advantages in stent migration compared with the uncovered stent.

Near-Infrared Fluorescence Imaging Using a Protease-Specific Probe for the Detection of Colon Tumors

BACKGROUND/AIMS Early tumor detection is crucial for the prevention of colon cancer. Near-infrared fluorescence (NIRF) imaging using a target-activatable probe may permit earlier disease detection. Matrix metalloproteinases (MMPs) participate in tumorigenesis and tumor growth. The aim of this study was to determine whether NIRF imaging using an MMP-activatable probe can detect colon tumors at early stages. METHODS WE UTILIZED TWO MURINE COLON CANCER MODELS: a sporadic colon cancer model induced by azoxymethane (AOM), and a colitis-associated cancer model induced by a combination of AOM and dextran sodium sulfate (DSS). Colonic lesions were analyzed by histologic examination, Western blotting, immunohistochemical staining, and NIRF imaging using an MMP-activatable probe. RESULTS Multiple variable-sized tumors developed in both models and progressed from adenomas to adenocarcinomas over time. At the early stage of the AOM/DSS model, diffuse inflammation was observed within the tumors. MMP expression increased progressively through normal, inflammation, adenoma, and adenocarcionoma stages. NIRF signal intensities were strongly correlated with each tumor stage from adenoma to adenocarcinoma. NIRF imaging also distinguished tumors from inflamed mucosa. CONCLUSIONS NIRF imaging using a protease-activatable probe may be a useful tool for early tumor detection. This approach could translate to improve the endoscopic detection of colon tumors, especially in patients with inflammatory bowel disease.

Clinicopathologic findings of colorectal traditional and sessile serrated adenomas in Korea: a multicenter study.

Background/Aims: Serrated polyps have emerged as important evidence supporting the serrated polyp-neoplasia pathway in colorectal carcinogenesis, an alternate to the classical adenoma-carcinoma sequence. However, there is confusion over the diagnostic criteria for serrated polyps including traditional serrated adenoma (TSA) and sessile serrated adenoma (SSA). In addition, clinical and pathologic characteristics of each are largely unknown and need further exploration. Methods: The 753 polyps that were previously diagnosed as serrated adenoma (SA) from 14 tertiary care university hospitals in Korea between 2003 and 2005 were evaluated for the clinicopathologic findings of TSA and SSA. Results: Among 753 cases, 420 (55.8%) were reclassified as TSA and 56 (7.4%) as SSA. Among the pathologic parameters, crypt branching, crypt dilatation, and horizontal crypts were more frequent in SSA than in TSA (p < 0.001). SSA was larger than TSA (12.6 ± 7.3 vs. 9.8 ± 6.9 mm, p = 0.005), was more likely to be flat type (p = 0.006), and was more frequently located in the proximal colorectum (p = 0.012). There were no significant differences in age, sex, and body mass index between TSA and SSA. Conclusions: Locationand endoscopic features of the polyps with abnormal crypt morphology in histologic findings could be helpful for the diagnosis and classification of SAs.

Colonic Perforation: Can We Manage It Endoscopically?

Colonic perforation occurs in a variety of clinical scenarios and colonoscopy-associated perforation is one of the important reasons for colonic perforation. Colonoscopy-associated perforation may be diagnosed during colonoscopy procedure by the visualization of evident colonic wall defect or, after the completion of colonoscopy, by the visualization of leaked air in the peritoneal or retroperitoneal space. Recently, the incidence of colonoscopy-associated perforation increased because of the introduction of colorectal endoscopic submucosal dissection. Traditionally, colonoscopy-associated perforation was managed surgically. However, medical management has been introduced widely and endoscopic clipping is the most important component for the medical management of colonoscopy-associated perforation. Timely administration of antibiotics is also important. Large perforations, diagnostic colonoscopy-associated perforations, large amount of pneumoperitoneum, and severe abdominal pain have been reported to be predictive of the necessity of surgery after endoscopic clipping. Surgery should be performed if patients show clinical deterioration even after the initiation of medical management.

Efficacy of Barium-Based Fecal Tagging for CT Colonography: a Comparison between the Use of High and Low Density Barium Suspensions in a Korean Population - a Preliminary Study

Objective This preliminarily study was designed to determine and to compare the efficacy of two commercially available barium-based fecal tagging agents for CT colonography (CTC) (high-density [40% w/v] and low-density [4.6% w/v] barium suspensions) in a population in Korea. Materials and Methods In a population with an identified with an average-risk for colorectal cancer, 15 adults were administered three doses of 20 ml 40% w/v barium for fecal tagging (group I) and 15 adults were administered three doses of 200 ml 4.6% w/v barium (group II) for fecal tagging. Excluding five patients in group I and one patient in group II that left the study, ten patients in group I and 14 patients in group II were finally included in the analysis. Two experienced readers evaluated the CTC images in consensus regarding the degree of tagging of stool pieces 6 mm or larger. Stool pieces were confirmed with the use of standardized CTC criteria or the absence of matched lesions as seen on colonoscopy. The rates of complete fecal tagging were analyzed on a per-lesion and a per-segment basis and were compared between the patients in the two groups. Results Per-lesion rates of complete fecal tagging were 52% (22 of 42; 95% CI, 37.7-66.6%) in group I and 78% (28 of 36; 95% CI, 61.7-88.5%) in group II. The difference between the two groups did not reach statistical significance (p = 0.285). The per-segment rates of complete tagging were 33% (6 of 18; 95% CI, 16.1%-56.4%) in group I and 60% (9 of 15; 95% CI, 35.7%-80.3%) in group II; again, the difference between the two groups did not reach statistical significance (p = 0.171). Conclusion Barium-based fecal tagging using both the 40% w/v and the 4.6% w/v barium suspensions showed moderate tagging efficacy. The preliminary comparison did not demonstrate a statistically significant difference in the tagging efficacy between the use of the two tagging agents, despite the tendency toward better tagging with the use of the 4.6% w/v barium suspension.