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).

Purpose: Advances in chemotherapeutic and targeted agents have increased pathologic complete response (pCR) rates after neoadjuvant systemic therapy (NST). Vacuum-assisted biopsy (VAB) has been suggested to accurately evaluate pCR. This study aims to confirm the non-inferiority of the 5-year disease-free survival of patients who omitted breast surgery when predicted to have a pCR based on breast magnetic resonance imaging (MRI) and VAB after NST, compared with patients with a pCR who had undergone breast surgery in previous studies. Methods The Omission of breast surgery for PredicTed pCR patients wIth MRI and vacuumassisted bIopsy in breaST cancer after neoadjuvant systemic therapy (OPTIMIST) trial is a prospective, multicenter, single-arm, non-inferiority study enrolling in 17 tertiary care hospitals in the Republic of Korea. Eligible patients must have a clip marker placed in the tumor and meet the MRI criteria suggesting complete clinical response (post-NST MRI size ≤ 1 cm and lesion-to-background signal enhancement ratio ≤ 1.6) after NST. Patients will undergo VAB, and breast surgery will be omitted for those with no residual tumor. Axillary surgery can also be omitted if the patient was clinically node-negative before and after NST and met the stringent criteria of MRI size ≤ 0.5 cm. Survival and efficacy outcomes are evaluated over five years.Discussion: This study seeks to establish evidence for the safe omission of breast surgery in exceptional responders to NST while minimizing patient burden. The trial will address concerns about potential undertreatment due to false-negative results and recurrence as well as improved patient-reported quality of life issues from the omission of surgery. Successful completion of this trial may reshape clinical practice for certain breast cancer subtypes and lead to a safe and less invasive approach for selected patients.

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.

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: 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 (wellmoderately 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).

Purpose: This study aimed to evaluate the long-term effect of esophagectomy in patients with esophageal squamous cell carcinoma (ESCC) by comparing the chemoradiotherapy (CRT)-only group and the trimodality treatment (TMT) group who received concurrent CRT followed by surgery. Materials and Methods: We included 412 operable ESCC patients treated with TMT or CRT between January 2005 and December 2015. The oncological outcomes of the two groups were compared using a weighted Cox proportional-hazards model with inverse probability of treatment weighting (IPTW). Results: The median survival time was 64 and 32 months in the TMT (n=270) and CRT (n=142) groups, respectively (p < 0.001). After IPTW, the median overall survival (OS) remained significantly higher in the TMT group than in the CRT group (61 months vs. 32 months, p=0.016). Moreover, the TMT group showed a better local recurrence-free rate (LRFR, p < 0.001) and distant metastasis-free rate (p=0.007). In the subgroup of patients with clinical complete response (cCR), the OS was not significantly different between the two groups, both before and after IPTW adjustment (p=0.35 and p=0.93). However, among non-cCR patients, the OS was significantly higher in the TMT group (64% vs. 45%, p < 0.001). Conclusion In patients with locally advanced ESCC, TMT was superior to CRT in terms of OS and LRFR. Such difference was more prominent in the non-cCR subgroup. In patients who achieved cCR, esophagectomy was effective in improving LRFR but not OS, suggesting that esophagectomy may be omitted in complete responders.

Purpose: We retrospectively evaluated the prognostic significance of lymph node ratio (LNR) in patients with esophageal squamous cell carcinoma who underwent neoadjuvant concurrent chemoradiation therapy (NCRT) followed by surgery. Materials and Methods: In total, 270 patients who underwent NCRT followed by surgery between August 2005 and December 2015 were included. They were divided into three groups: LNR 0 (n = 196), LNR low (0 < LNR ≤ 0.1; n = 63), and LNR high (>0.1; n = 11). The primary endpoint was overall survival (OS), and the secondary endpoints were freedom from local recurrence (FFLR), distant metastasis-free survival (DMFS), and disease-free survival (DFS). Results: The median number of retrieved lymph nodes per patient was 33. Pathologically, 74 patients had positive lymph nodes. The median follow-up duration was 36.1 months, and the median survival period was 68.4 months. There was a significant correlation between LNR and the number of positive lymph nodes (correlation coefficient = 0.763, p < 0.001). There was a substantial difference in the OS among the LNR groups, with 2-year survival rates of 79.0%, 54.0%, and 9.1% in the LNR 0, LNR low, and LNR high groups, respectively (p < 0.001). A marked decrease in FFLP, DMFS, and DFS was observed with the increasing LNR. In subgroup analysis, the survival results of patients with clinically positive lymph node were similar from those of entire cohort. Conclusion LNR is a significant prognostic factor in patients with esophageal squamous cell carcinoma who underwent NCRT followed by surgery. Additional treatment and closer follow-up would be necessary for patients with a high LNR.

Objectives: The Korea Centers for Disease Control and Prevention has published “A Guideline for Unknown Disease Outbreaks (UDO).” The aim of this report was to introduce tabletop exercises (TTX) to prepare for UDO in the future. Methods: The UDO Laboratory Analyses Task Force in Korea Centers for Disease Control and Prevention in April 2018, assigned unknown diseases into 5 syndromes, designed an algorithm for diagnosis, and made a panel list for diagnosis by exclusion. Using the guidelines and laboratory analyses for UDO, TTX were introduced. Results: Since September 9th , 2018, the UDO Laboratory Analyses Task Force has been preparing TTX based on a scenario of an outbreak caused by a novel coronavirus. In December 2019, through TTX, individual missions, epidemiological investigations, sample treatments, diagnosis by exclusions, and next generation sequencing analysis were discussed, and a novel coronavirus was identified as the causal pathogen. Conclusion Guideline and laboratory analyses for UDO successfully applied in TTX. Conclusions drawn from TTX could be applied effectively in the analyses for the initial response to COVID-19, an ongoing epidemic of 2019 - 2020. Therefore, TTX should continuously be conducted for the response and preparation against UDO.

Purpose: We retrospectively evaluated the prognostic significance of lymph node ratio (LNR) in patients with esophageal squamous cell carcinoma who underwent neoadjuvant concurrent chemoradiation therapy (NCRT) followed by surgery. Materials and Methods: In total, 270 patients who underwent NCRT followed by surgery between August 2005 and December 2015 were included. They were divided into three groups: LNR 0 (n = 196), LNR low (0 < LNR ≤ 0.1; n = 63), and LNR high (>0.1; n = 11). The primary endpoint was overall survival (OS), and the secondary endpoints were freedom from local recurrence (FFLR), distant metastasis-free survival (DMFS), and disease-free survival (DFS). Results: The median number of retrieved lymph nodes per patient was 33. Pathologically, 74 patients had positive lymph nodes. The median follow-up duration was 36.1 months, and the median survival period was 68.4 months. There was a significant correlation between LNR and the number of positive lymph nodes (correlation coefficient = 0.763, p < 0.001). There was a substantial difference in the OS among the LNR groups, with 2-year survival rates of 79.0%, 54.0%, and 9.1% in the LNR 0, LNR low, and LNR high groups, respectively (p < 0.001). A marked decrease in FFLP, DMFS, and DFS was observed with the increasing LNR. In subgroup analysis, the survival results of patients with clinically positive lymph node were similar from those of entire cohort. Conclusion LNR is a significant prognostic factor in patients with esophageal squamous cell carcinoma who underwent NCRT followed by surgery. Additional treatment and closer follow-up would be necessary for patients with a high LNR.

PURPOSE: The optimal treatment for synchronous liver metastasis (LM) from colorectal cancer (CRC) depends on various factors. The present study was intended to investigate the oncologic outcome according to the time of resection of metastatic lesions. METHODS: Data from patients who underwent treatment with curative intent for primary CRC and synchronous LM between 2004 and 2009 from 9 university hospitals in Korea were collected retrospectively. One hundred forty-three patients underwent simultaneous resection for primary CRC and synchronous LM (simultaneous surgery group), and 65 patients were treated by 2-stage operation (staged surgery group). RESULTS: The mean follow-up length was 41.2 ± 24.6 months. In the extent of resection for hepatic metastasis, major hepatectomy was more frequently performed in staged surgery group (33.8% vs. 8.4%, P < 0.001). The rate of severe complications of Clavien-Dindo classification grade III or more was not significantly different between the 2 groups. The 3-year overall survival (OS) rate was 85.0% in staged surgery group and 69.4% in simultaneous surgery group (P = 0.013), and the 3-year recurrence-free survival (RFS) rate was 46.4% in staged surgery group and 30.2% in simultaneous surgery group (P = 0.143). In subgroup analysis based on the location of primary CRC, the benefit of staged surgery for OS and RFS was clearly shown in rectal cancer (P = 0.021 and P = 0.015). CONCLUSION: Based on our results, staged surgery with or without neoadjuvant chemotherapy should be considered for resectable synchronous LM from CRC, especially in rectal cancer, as a safe and fairly promising option.
Classification ; Colorectal Neoplasms ; Drug Therapy ; Follow-Up Studies ; Hepatectomy ; Hospitals, University ; Humans ; Korea ; Liver ; Neoplasm Metastasis ; Rectal Neoplasms ; Retrospective Studies