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Background/aims: : The gut microbiome has emerged as a key player that mechanistically links various risk factors to colorectal cancer (CRC) etiology. However, the role of the gut microbiome in CRC pathogenesis remains unclear. This study aimed to characterize the gut microbiota in healthy controls (HCs) and patients with colorectal adenoma (AD) and CRC in subgroups based on sex and age., Methods: : Study participants who visited the hospital for surveillance of CRC or gastrointestinal symptoms were prospectively enrolled, and the gut microbiome was analyzed based on fecal samples., Results: : In terms of HC-AD-CRC sequence, commensal bacteria, including lactate-producing ( Streptococcus salivarius ) and butyrate-producing ( Faecalibacterium prausnitzii, Anaerostipes hadrus, and Eubacterium hallii ) bacteria, were more abundant in the HC group than in the AD and CRC groups. In the sex comparison, the female HC group had more lactate-producing bacteria ( Bifidobacterium adolescentis, Bifidobacterium catenulatum, and Lactobacillus ruminis ) than the male HC group. In age comparison, younger subjects had more butyrate-producing bacteria ( Agathobaculum butyriciproducens and Blautia faecis ) than the older subjects in the HC group. Interestingly, lactate-producing bacteria ( B. catenulatum ) were more abundant in females than males among younger HC group subjects. However, these sex- and age-dependent differences were not observed in the AD and CRC groups., Conclusions: : The gut microbiome, specifically lactate- and butyrate-producing bacteria, which were found to be abundant in the HC group, may play a role in preventing the progression of CRC. In particular, lactate-producing bacteria, which were found to be less abundant in healthy male controls may contribute to the higher incidence of CRC in males.

Background/aims: Synchronous multiple gastric cancer (SMGC) accounts for approximately 6% to 14% of gastric cancer (GC) cases. This study aimed to identify risk factors for SMGC., Methods: A total of 14,603 patients diagnosed with GC were prospectively enrolled. Data including age, sex, body mass index, smoking, alcohol consumption, family history, p53 expression, microsatellite instability, cancer classification, lymph node metastasis, and treatment were collected. Risk factors were analyzed using logistic regression analysis between a single GC and SMGC., Results: The incidence of SMGC was 4.04%, and that of early GC (EGC) and advanced GC (AGC) was 5.43% and 3.11%, respectively. Patients with SMGC were older (65.33 years vs 61.75 years, p<0.001) and more likely to be male. Lymph node metastasis was found in 27% of patients with SMGC and 32% of patients with single GC. Multivariate analysis showed that SMGC was associated with sex (male odds ratio [OR], 1.669; 95% confidence interval [CI], 1.223 to 2.278; p=0.001), age (≥65 years OR, 1.532; 95% CI, 1.169 to 2.008; p=0.002), and EGC (OR, 1.929; 95% CI, 1.432 to 2.600; p<0.001). Survival rates were affected by Lauren classification, sex, tumor size, cancer type, distant metastasis, and venous invasion but were not related to the number of GCs. However, the survival rate of AGC with SMGC was very high., Conclusions: SMGC had unique characteristics such as male sex, older age, and EGC, and the survival rate of AGC, in which the intestinal type was much more frequent, was very good (Trial registration number: NCT04973631).

Background/aims: : The genetic expression in the active inflammatory regions is increased in ulcerative colitis (UC) with endoscopic activity. The aim of this study was to investigate the molecular activity of inflammation and tissue remodeling markers in endoscopically inflamed and uninflamed regions of UC., Methods: : Patients with UC (n=47) and controls (n=20) were prospectively enrolled at the Seoul National University Bundang Hospital. Inflamed tissue was obtained at the most active lesion, and uninflamed tissue was collected from approximately 15 cm above the upper end of the active lesion via colonoscopic biopsies. The messenger RNA expression levels of transforming growth factor β ( TGF-β ), interleukin ( IL)-1β , IL-6 , IL-17A , E-cadherin , olfactomedin-4 ( OLFM4 ), leucine-rich repeat-containing G protein-coupled receptor 5 ( LGR5 ), vimentin , fibroblast-specific protein-1 ( FSP1 ), and α-smooth muscle actin ( SMA ) were evaluated. Mucosal healing (MH) was defined according to a Mayo endoscopic score of 0, 1 or non-MH (Mayo endoscopic score of 2 or 3)., Results: : The messenger RNA expressions of TGF-β , IL-1β , OLFM4 , FSP1 , vimentin , and α-SMA were significantly higher, and that of E-cadherin was significantly lower in inflamed and uninflamed regions of patients with UC than those in controls. In the inflamed regions, patients in the non-MH group had significantly increased genetic expression of TGF-β , FSP1 , vimentin , and α-SMA compared to patients in the MH group. Similarly, the non-MH group had significantly higher genetic expression of TGF-β , IL-1β , IL-6 , vimentin , and α-SMA than the MH group in the uninflamed regions., Conclusions: : Endoscopic activity in UC suggests inflammation and tissue remodeling of uninflamed regions similar to inflamed regions (ClinicalTrials.gov, NCT05653011).

Background/aims: There are few reports regarding mixed carcinoma, defined as a mixture of glandular and poorly cohesive components, in patients with gastric cancer (GC). The aim of this study was to evaluate the proportion and characteristics of mixed carcinoma in GC patients., Methods: A total of 7,215 patients diagnosed with GC at Seoul National University Bundang Hospital were enrolled from March 2011 to February 2020. GC was divided into four groups (well-moderately differentiated GC, poorly differentiated GC, poorly cohesive carcinoma, and mixed carcinoma). The proportion of each GC type and the clinicopathological features were analyzed and divided into early GC and advanced GC., Results: The proportion of mixed carcinoma was 10.9% (n=787). In early GC, submucosal invasion was the most common in poorly differentiated (53.7%), and mixed carcinoma ranked second (41.1%). Mixed carcinoma showed the highest proportion of lymph node metastasis in early GC (23.0%) and advanced GC (78.3%). In advanced GC, the rate of distant metastasis was 3.6% and 3.9% in well-moderately differentiated GC and mixed carcinoma, respectively, lower than that in poorly differentiated GC (6.4%) and poorly cohesive carcinoma (5.7%), without statistical significance., Conclusions: Mixed carcinoma was associated with lymph node metastasis compared to other histological GC subtypes. And it showed relatively common submucosal invasion in early GC, but the rates of venous invasion and distant metastasis were lower in advanced GC. Further research is needed to uncover the mechanism underlying these characteristics of mixed carcinoma (Trial registration number: NCT04973631).

Background/aims: The incidence and prognosis of gastric cancer (GC) shows sex difference. This study aimed to evaluate the effect of body mass index (BMI) on GC survival depending on sex., Methods: The sex, age, location, histology, TNM stages, BMI, and survival were analyzed in GC patients from May 2003 to February 2020 at the Seoul National University Bundang Hospital., Results: Among 14,688 patients, there were twice as many males (66.6%) as females (33.4%). However, under age 40 years, females (8.6%) were more prevalent than males (3.1%). Cardia GC in males showed a U-shaped distribution for underweight (9.6%), normal (6.4%), overweight (6.1%), obesity (5.6%), and severe obesity (9.3%) but not in females (p=0.003). Females showed decreased proportion of diffuse-type GC regarding BMI (underweight [59.9%], normal [56.8%], overweight [49.5%], obesity [44.8%], and severe obesity [41.7%]), but males did not (p<0.001). Both sexes had the worst prognosis in the underweight group (p<0.001), and the higher BMI, the better prognosis in males, but not females. Sex differences in prognosis according to BMI tended to be more prominent in males than in females in subgroup analysis of TNM stages I, II, and III and the operative treatment group., Conclusions: GC-specific survival was affected by BMI in a sex-dependent manner. These differences may be related to genetic, and environmental, hormonal factors; body composition; and muscle mass (Trial registration number: NCT04973631).

Background/aims: Helicobacter pylori (HP) infection is positively associated with metabolic syndrome (MS). However, the long-term effects of eradication therapy on MS and sex differences have not been thoroughly studied. We aimed to investigate the long-term effects of HP eradication on MS and sex differences., Methods: This study included 2,267 subjects who visited a tertiary referral center between May 2003 and May 2019. HP was diagnosed by histology, a Campylobacter-like organism test, and culture, and the subjects were prospectively followed up. The participants were categorized into three groups: HP uninfected, HP infected but non-eradicated, and HP eradicated. The baseline characteristics and changes in metabolic parameters after HP eradication were compared over a 5-year follow-up period., Results: Among 1,521 subjects, there was no difference in baseline metabolic parameters between the HP-uninfected (n=509) and HP-infected (n=1,012) groups, regardless of sex. Analysis of the metabolic parameters during follow-up among HP-uninfected (n=509), HP-non-eradicated (n=346), and HP-eradicated (n=666) groups showed that high-density lipoprotein (HDL) and the body mass index (BMI) increased after eradication, with a significant difference at 1-year of follow-up. In females, HDL increased after eradication (p=0.023), and the BMI increased after eradication in male subjects (p=0.010). After propensity score matching, the HDL change in female remained significant, but the statistical significance of the change in BMI in the male group became marginally significant (p=0.089)., Conclusions: HP eradication affected metabolic parameters differently depending on sex. HDL significantly increased only in females over time, especially at 1-year of follow-up. In contrast, BMI showed an increasing tendency over time in males, especially at the 1-year follow-up.