Hyo-Joon Yang

Field Cancerization in Sporadic Colon Cancer

Background/Aims Aberrant DNA methylation has a specific role in field cancerization. Certain molecular markers, including secreted frizzled-related protein 2 (SFRP2), tissue factor pathway inhibitor 2 (TFPI2), N-Myc downstream-regulated gene 4 (NDRG4) and bone morphogenic protein 3 (BMP3), have previously been shown to be hypermethylated in colorectal cancer (CRC). We aim to examine field cancerization in CRC based on the presence of aberrant DNA methylation in normal-appearing tissue from CRC patients. Methods We investigated promoter methylation in 34 CRC patients and five individuals with normal colonoscopy results. CRC patients were divided into three tissue groups: tumor tissue, adjacent and nonadjacent normal-appearing tissue. The methylation status (positive: methylation level >20%) of SFRP2, TFPI2, NDRG4, and BMP3 promoters was investigated using methylation-specific PCR. Results The methylation frequencies of the SFRP2, TFPI2, NDRG4 and BMP3 promoters in tumor/adjacent/nonadjacent normal-appearing tissue were 79.4%/63.0%/70.4%, 82.4%/53.6%/60.7%, 76.5%/61.5%/69.2%, 41.2%/35.7%/50.0%, respectively. The methylation levels of the SFRP,TFPI2, NDRG4 and BMP3 promoters in tumor tissues were significantly higher than those in normal-appearing tissue (SFRP2, p=0.013; TFPI2, p<0.001; NDRG4, p=0.003; BMP3, p=0.001). No significant correlation was observed between the methylation levels of the promoters and the clinicopathological variables. Conclusions The field effect is present in CRC and affects both the adjacent and nonadjacent normal-appearing mucosa.

Miss rate of colorectal neoplastic polyps and risk factors for missed polyps in consecutive colonoscopies

Background/Aims Colonoscopic polypectomy is the best diagnostic and therapeutic tool to detect and prevent colorectal neoplasms. However, previous studies have reported that 17% to 28% of colorectal polyps are missed during colonoscopy. We investigated the miss rate of neoplastic polyps and the factors associated with missed polyps from quality-adjusted consecutive colonoscopies. Methods We reviewed the medical records of patients who were found to have colorectal polyps at a medical examination center of the Kangbuk Samsung Hospital between March 2012 and February 2013. Patients who were referred to a single tertiary academic medical center and underwent colonoscopic polypectomy on the same day were enrolled in our study. The odds ratios (ORs) associated with polyp-related and patient-related factors were evaluated using logistic regression analyses. Results A total of 463 patients and 1,294 neoplastic polyps were analyzed. The miss rates for adenomas, advanced adenomas, and carcinomas were 24.1% (312/1,294), 1.2% (15/1,294), and 0% (0/1,294), respectively. Flat/sessile-shaped adenomas (adjusted OR, 3.62; 95% confidence interval [CI], 2.40–5.46) and smaller adenomas (adjusted OR, 5.63; 95% CI, 2.84– 11.15 for ≤5 mm; adjusted OR, 3.18; 95% CI, 1.60–6.30 for 6–9 mm, respectively) were more frequently missed than pedunculated/sub-pedunculated adenomas and larger adenomas. In patients with 2 or more polyps compared with only one detected (adjusted OR, 2.37; 95% CI, 1.55–3.61 for 2–4 polyps; adjusted OR, 11.52; 95% CI, 4.61–28.79 for ≥5 polyps, respectively) during the first endoscopy, the risk of missing an additional polyp was significantly higher. Conclusions One-quarter of neoplastic polyps was missed during colonoscopy. We encourage endoscopists to detect smaller and flat or sessile polyps by using the optimal withdrawal technique.

Clinical characteristics of primary gastric lymphoma detected during screening for gastric cancer in Korea.

The role of screening endoscopy in primary gastric lymphoma (PGL) has not been investigated. This study aimed to evaluate the clinical characteristics and outcomes of PGLs detected by screening endoscopy in the high prevalence area of Helicobacter pylori (H. pylori) infection.

Randomized trial comparing oral sulfate solution with 4‐L polyethylene glycol administered in a split‐dose as preparation for colonoscopy

The present study aimed to evaluate the non‐inferiority of low‐volume oral sulfate solution (OSS) to 4‐L polyethylene glycol (PEG) solutions administered in a split‐dose regimen as bowel preparation for colonoscopy. The safety and tolerability were also compared between the two regimens.

External Validation of the Endoscopic Features of Sessile Serrated Adenomas in Expert and Trainee Colonoscopists

Background/Aims It is unclear whether the endoscopic features of sessile serrated adenomas (SSAs) would be useful to trainee colonoscopists to predict SSA. Therefore, the present study aimed to identify features that expert and trainee colonoscopists can use to independently and reliably predict SSA by using high-resolution white-light endoscopy. Methods Endoscopic images of 81 polyps (39 SSAs, 22 hyperplastic polyps, and 20 tubular adenomas) from 43 patients were retrospectively evaluated by 10 colonoscopists (four experts and six trainees). Eight endoscopic features of SSAs were assessed for each polyp. Results According to multivariable analysis, a mucous cap (odds ratio [OR], 10.44; 95% confidence interval [CI], 5.72 to 19.07), indistinctive borders (OR, 4.21; 95% CI, 2.74 to 7.16), dark spots (OR, 3.64; 95% CI, 1.89 to 7.00), and cloud-like surface (OR, 2.43; 95% CI, 1.27 to 4.668) were independent predictors of SSAs. Among these, a mucous cap, indistinctive borders, and cloud-like surface showed moderate interobserver agreement (mean κ >0.40) among experts and trainees. When ≥1 of the three predictors was observed, the sensitivity and specificity for diagnosing SSAs were 79.0% and 81.4%, respectively. Conclusions Colonoscopy trainees and experts can use several specific endoscopic features to independently and reliably predict SSAs.

Weight loss and waist reduction is associated with improvement in gastroesophageal disease reflux symptoms: A longitudinal study of 15 295 subjects undergoing health checkups.

General obesity and abdominal obesity is an established risk factor of gastroesophageal reflux disease (GERD). However, the influence of weight or waist change on improvement of GERD is unclear. Our aim was to investigate if weight loss or waist reduction improves GERD symptoms and esophagitis.

Derivation and validation of a risk scoring model to predict advanced colorectal neoplasm in adults of all ages

Little is known about how to include adults < 50 years in colonoscopy screening. This study aimed to derive a risk‐scoring model incorporating laboratory indicators for metabolic risks to predict advanced colorectal neoplasia (ACN) in asymptomatic Korean adults both younger and older than 50 years.

Continuous Use of Thienopyridine May Be as Safe as Low-Dose Aspirin in Endoscopic Resection of Gastric Tumors

Background/Aims Current guidelines recommend withholding antiplatelets for 5–7 days before high-risk endoscopic procedures. We investigated whether this reduces post-endoscopic submucosal dissection (ESD) bleeding. Methods Gastric ESD cases with antiplatelets were retorospectively reviewed. Withholding antiplatelets for 5–7 days before ESD was defined as cessation and 0–4 days as continuation. The rate and risk of post-ESD bleeding according to the types and cessation of antiplatelets were assessed. Results Among the 215 patients (117 adenoma and 98 early gastric cancer), 161 patients were on single (94 aspirin, 56 thienopyridine, and 11 other agents), 51 on dual, and 3 on triple antiplatelets. Post-ESD bleeding rates were 12.8% in aspirin users, 3.6% in thienopyridine, 27.5% in dual, 33.3% in triple therapy, and 9.7% in the cessation and 15.0% in the continuation group. Multiple antiplatelets (odds ratio [OR], 2.41; 95% confidence interval [CI], 1.01 to 5.76) and specimen size ≥ 5.5 cm (OR, 2.84; 95% CI, 1.04 to 7.73) were the risk of bleeding, while continuation of thienopyridine (OR, 0.23; 95% CI, 0.05 to 1.09) and antiplatelets (OR, 1.83; 95% CI, 0.68 to 4.94) did not increase the risk of bleeding. Conclusions Continuing thienopyridine and aspirin did not increase the risk of post-ESD. Multiple antiplatelet therapy and a large specimen size were independent risk factors of post-ESD bleeding.

Nonalcoholic Fatty Liver Disease Is Associated with Increased Risk of Reflux Esophagitis

AbstractBackgroundReflux esophagitis is associated with obesity and metabolic syndrome; however, the relationship between nonalcoholic fatty liver disease (NAFLD) and reflux esophagitis is unclear.AimWe examined the association between NAFLD and the development of reflux esophagitis.MethodsOur cohort consisted of 117,377 Korean adults without reflux esophagitis at baseline who underwent a health checkup program including upper endoscopy between 2002 and 2014 and were followed annually or biennially until December 2014. NAFLD was defined as hepatic steatosis on ultrasonography in the absence of excessive alcohol use or any other identifiable cause.ResultsOver 520,843.2 person-years of follow-up, 22,500 participants developed reflux esophagitis (incidence density, 43.2 per 1000 person-years). In models adjusted for age and sex, the adjusted hazard ratio (aHR) (95% confidence interval [CI]) for incident reflux esophagitis in subjects with NAFLD compared to those without was 1.16 (1.13–1.20). After further adjustment for confounders of center, year of visit, smoking status, alcohol intake, regular exercise, education level, and body mass index, the association between NAFLD and incident reflux esophagitis was attenuated, but remained significant (aHR 1.06; 95% CI 1.02–1.10).ConclusionsIn this large cohort of Korean men and women, participants with NAFLD exhibited increased incidence of reflux esophagitis independent of possible confounders, suggesting that NAFLD contributes to the development of reflux esophagitis.

Microsatellite Instability Status of Interval Colorectal Cancers in a Korean Population.

Background/Aims A subset of patients may develop colorectal cancer after a colonoscopy that is negative for malignancy. These missed or de novo lesions are referred to as interval cancers. The aim of this study was to determine whether interval colon cancers are more likely to result from the loss of function of mismatch repair genes than sporadic cancers and to demonstrate microsatellite instability (MSI). Methods Interval cancer was defined as a cancer that was diagnosed within 5 years of a negative colonoscopy. Among the patients who underwent an operation for colorectal cancer from January 2013 to December 2014, archived cancer specimens were evaluated for MSI by sequencing microsatellite loci. Results Of the 286 colon cancers diagnosed during the study period, 25 (8.7%) represented interval cancer. MSI was found in eight of the 25 patients (32%) that presented interval cancers compared with 22 of the 261 patients (8.4%) that presented sporadic cancers (p=0.002). In the multivariable logistic regression model, MSI was associated with interval cancer (OR, 3.91; 95% confidence interval, 1.38 to 11.05). Conclusions Interval cancers were approximately four times more likely to show high MSI than sporadic cancers. Our findings indicate that certain interval cancers may occur because of distinct biological features.