This prospective multicenter cohort study aimed to assess the effectiveness and safety of bariatric and metabolic surgery (BMS) in Korean patients with class II obesity or higher and those with a body mass index (BMI) ≥ 27.5 kg/m². Between September 2020 and December 2022, 116 patients undergoing BMS were enrolled from nine centers in Korea. Of these, 37 patients underwent gastric bypass and 79 underwent sleeve gastrectomy. Follow-up evaluations were performed for up to 2 years. Clinical data were collected alongside four quality of life (QOL) surveys (EQ-5D, IWQOL-lite, OP-scale, and BAROS) administered at 12, 24, 48, 72, and 96 weeks postoperatively. Clinical parameters included obesity severity, complications by surgery type, associated medical problems, nutritional status, and their longitudinal changes. The cohort had a mean age of 37.0 ± 11.1 years and a mean BMI of 41.9 ± 7.6 kg/m²; 71.6

157 Background: Gastrectomy can induce improvement in type 2 diabetes (T2DM), yet the metabolic impact may vary according to reconstruction method. Whether reconstruction strategy influences diabetes outcomes in gastric cancer remains unclear. The STARDOM trial was designed to determine the differential metabolic effects of Billroth II (BII), conventional Roux-en-Y (CRY), and long-limb Roux-en-Y (LRY) reconstruction after subtotal gastrectomy. Methods: STARDOM is a prospective, multicenter, phase III randomized controlled trial enrolling patients with stage I–II distal gastric adenocarcinoma, T2DM, and BMI ≥23 kg/m². Patients were randomized 1:1:1 to BII, CRY, or LRY reconstruction. The primary endpoint is biochemical improvement of diabetes at 12 months, defined as HbA1c <6.5% without antidiabetic medication. We report prespecified 6-month interim outcomes. Results: Sixty patients were randomized (BII n=20, CRY n=19, LRY n=21) with balanced baseline characteristics. At 6 months, HbA1c <6.5% was achieved in 28.6% of BII, 53.8% of CRY, and 70.6% of LRY patients. LRY demonstrated a significantly higher response rate compared with BII (p=0.032), representing more than a twofold increase in diabetes control. Mean HbA1c at 6 months was lowest in LRY (6.17%) compared with CRY (6.55%) and BII (6.50%). Weight loss was comparable across groups, suggesting a weight-independent metabolic effect. Surgical morbidity did not differ significantly. Conclusions: Long-limb Roux-en-Y reconstruction produced superior early glycemic control compared with Billroth II after gastrectomy for gastric cancer, without increased morbidity. These findings support reconstruction-dependent metabolic benefit and may influence surgical strategy in patients with gastric cancer and T2DM. (ClinicalTrial.gov ID: NCT04284943.) Clinical trial information: NCT04284943 . Six-month outcomes from the STARDOM trial. Billroth II (n=14) Conventional RY (n=13) Long-limb RY (n=17) P value CRY vs BII LRY vs BII LRY vs BII Glycated hemoglobin Level, n (%) < 6.5% 4 (28.6%) 7 (53.8%) 12 (70.6%) 0.066 0.252 0.032 < 6.0% 2 (14.3%) 5 (38.5%) 7 (41.2%) 0.231 0.209 0.132 At baseline, %, mean (SD) 8.1 (1.5) 7.7 (0.9) 8.0 (1.6) 0.741 0.382 0.755 At 6 months, %, mean (SD) 6.5 (0.6) 6.6 (0.9) 6.2 (1.0) 0.416 0.856 0.268 Fasting glucose At baseline, mg/dL, mean (SD) 163.9 (107.4) 183.5 (74.0) 156.8 (56.1) 0.660 0.582 0.827 At 6 months, mg/dL, mean (SD) 121.2 (37.8) 129.9 (28.9) 119.1 (18.9) 0.580 0.506 0.852 Change from baseline, mg/dL, mean (SD) -42.6 (113.7) -53.6 (68.9) -37.7 (62.8) 0.874 0.763 0.886 Abbreviations: BII, Billroth II; CRY, conventional Roux-en-Y; LRY, long-limb Roux-en-Y; HbA1c, glycated hemoglobin; SD, standard deviation; BMI, body mass index.

Background/Objectives: Fat-free mass (FFM) loss after metabolic and bariatric surgery (MBS) is associated with adverse long-term outcomes, including osteoporosis. Identifying biomarkers that predict excessive FFM loss can improve perioperative patient management and postoperative risk stratification. This study investigated whether preoperative amino acid metabolite (AAM) levels could predict excessive FFM loss after laparoscopic sleeve gastrectomy (LSG). Methods: Forty patients with morbid obesity who underwent LSG between 2019 and 2020 were retrospectively analyzed. Based on the FFM loss to body weight loss ratio (%FFML/BWL) at 3 months postoperatively, patients were categorized into excessive (>25%) and non-excessive (≤25%) FFM loss groups. Anthropometric measurements and serum sampling were performed preoperatively and at 3, 6, and 12 months postoperatively. AAM profiles were collected before surgery. Statistical analyses, including logistic regression and receiver operating characteristic curves, were performed. Results: Twenty-five patients showed excessive FFM loss 3 months after surgery. They had significantly lower preoperative tyrosine (Tyr) levels (p = 0.025). Logistic regression revealed that higher Tyr levels were significantly associated with lower odds of being male, suggesting a potential protective effect (odds ratio (OR) =0.019, p = 0.010). Tyr profiling demonstrated acceptable predictive performance (area under the curve =0.715, p = 0.025). Despite nonsignificant p-values, trends showed lower FFM and muscle mass and higher fat mass in the excessive FFM loss group throughout follow-up. Conclusions: Preoperative Tyr profiling may help identify patients at risk for excessive FFM loss. These findings support prioritizing metabolic health alongside total weight loss in the evaluation of MBS outcomes.

Obesity has emerged as a major global health issue. The ratio of male to female patients undergoing metabolic bariatric surgery (MBS) is 1:3.5. Although not as dramatic compared to the global trend, the rate of obesity in women of reproductive age in Korea has been steadily increasing over the past several decades. The impact of obesity on reproductive health and perinatal outcomes should be carefully considered when consulting female candidates of reproductive age for MBS. Obesity adversely affects reproductive health by causing menstrual irregularities, anovulation, subfertility, and increased miscarriage risk, as well as impairing the success of assisted reproductive technologies. Maternal obesity also heightens the risk of adverse perinatal outcomes, including childhood obesity and metabolic disorders. MBS has been shown to improve fertility outcomes and reduce obesity-related pregnancy complications, although concerns remain regarding potential risks such as small-for-gestational-age infants due to rapid weight loss and nutritional deficiencies. Despite these implications, current MBS guidelines rarely address the unique needs of reproductive-age women. In response, the Korean Society for Metabolic and Bariatric Surgery convened a task force to develop evidence-based recommendations tailored to this population. This position statement aims to guide the management of obesity in women of reproductive age to optimize reproductive and perinatal outcomes.

Peritoneal metastasis (PM) is a major challenge in advanced gastric cancer (GC) with poor prognosis. Normothermic intraperitoneal and systemic treatment (NIPS) has become a promising therapeutic approach. This consensus aims to provide practical recommendations for NIPS treatment for gastric cancer with peritoneal metastasis (GCPM). The GRADE standards were used to rank evidence, and the Delphi method was employed for expert voting. 30 experts from China, Japan, South Korea, and Singapore participated in the development of this consensus. 28 experts participated in the voting process, which produced 29 statements covering diagnostic approaches, patient selection criteria, treatment regimens, management of intraperitoneal port placement, and conversion surgery considerations, and post-surgical treatment strategies in NIPS therapy. Based on current evidence and expert experience, these statements aim to improve the clinical outcomes of NIPS therapy for GCPM patients.

Purpose Recent studies have investigated intraperitoneal paclitaxel (IP PTX) combined with systemic chemotherapy for the treatment of gastric cancer peritoneal metastases (GCPM). This clinical trial integrated translational study was conducted to identify biomarkers that can predict patient responses to IP PTX plus systemic systemic S-1 plus oxaliplatin (SOX) chemotherapy. Materials and methods Patients from the PIPS-GC phase Ib/II clinical trial, enrolled at the Korea University Guro Hospital, were included in analyses. Whole exome and transcriptome sequencing were performed on formalin-fixed, paraffin-embedded gastric tumor, normal gastric, and peritoneal tumor tissues. A metastatic tumor-specific gene set was analyzed using The Cancer Genome Atlas (TCGA) gastric cancer data and publicly available single-cell RNA sequencing (scRNA-seq) datasets. Spatial transcriptomic analysis of primary and peritoneal tumors from a non-responder was performed to validate candidate biomarkers. Results Nine patients with gastric cancer were enrolled; six in the response group and three in the non-response group. Candidate genes for predicting IP PTX plus systemic SOX chemotherapy response were identified and compared with TCGA-GC and scRNA-seq datasets. Spatial transcriptomics revealed higher expression of thrombospondin type 1 domain-containing protein 4 (THSD4) in peritoneal tumors, which was associated with chemotherapy resistance via midkine and epithelial-mesenchymal transition pathways. Conclusion This PIPS-GC clinical trial identified THSD4 as a potential biomarker for predicting IP PTX plus systemic SOX response in gastric cancer peritoneal metastasis. Further research is required to elucidate the mechanism of action by which THSD4 affects GCPM and validate its clinical utility as a predictive biomarker for IP PTX response.

BACKGROUND:Long-limb Roux-en-Y (LLRY) reconstruction has recently been implemented as an oncometabolic surgery to improve glycemic control following surgery for gastric cancer (GC); however, data on its feasibility are insufficient. We investigated the 1-year outcomes of LLRY reconstruction for glycemic control in patients with type 2 diabetes (T2D). METHODS:We reviewed the records of 15 patients with GC and T2D who underwent LLRY reconstruction after gastrectomy, with biliopancreatic and Roux limb lengths of 130-250 cm, to improve postoperative glycemic control. The primary outcome was the T2D remission (glycated hemoglobin <6.5% without antidiabetic medication) rate at 12 months postoperatively. The diabetes prediction (DP) score and Korean nationwide average T2D remission rates following GC surgery were compared. RESULTS:The mean patient age was 66.5 years (standard deviation [SD] 9.6), mean body mass index was 26.4 kg/m2 (SD 4.4), and mean glycated hemoglobin level was 7.7% (SD 1.5). The overall T2D remission rate was 46.7%. The postoperative T2D remission rate was 12.9% higher than the DP score estimate (33.8%) and 25.7% higher than the Korean national average rate (21%) of T2D remission following GC surgery. CONCLUSION:Our results show that LLRY reconstruction after gastrectomy is an effective oncometabolic surgery for treating T2D and GC.

BACKGROUND:Patients with peritoneal metastasis from gastric cancer show poor prognosis with standard systemic chemotherapy. This prospective multicenter phase II clinical trial was performed to evaluate the efficacy and safety of intraperitoneal paclitaxel combined with systemic S-1 plus oxaliplatin for patients with advanced or recurrent gastric cancer with peritoneal metastasis. PATIENT AND METHOD:Patients with advanced or recurrent gastric cancer with histologically or radiologically confirmed peritoneal metastases were eligible for the study. The chemotherapy regimen consisted of eight cycles of intraperitoneal paclitaxel 80 mg/m2 on days 1 and 8, combined with 80 mg/m2 S-1 for days 1-14, and 100 mg/m2 oxaliplatin on day 1, repeated every 21 days. The primary endpoint was 6-month progression-free survival. One-year progression-free and overall survival, response rate, and safety were set as the secondary endpoints. RESULT:In total, 28 patients were included in the study, of which 24 were analyzed, with the exception of those lost to follow-up and withdrawal of consent. The 6-months progression-free survival was 82.6 % (95 % CI: 68.5-99.6 %). The one-year progression-free and overall survival rates were 69.6 % (95 % CI: 53.1-91.2 %) and 76.9 % (95 % CI: 61-97 %), respectively. The overall response rate was 41.67 %. The hematologic toxicity profile showed grade 3/4 hematologic toxicities such as leukopenia (20.8 %), neutropenia (41.7 %), and thrombocytopenia (8.3 %). The only non-hematologic adverse event was grade 3 diarrhea. Three (12.5 %) patients experienced intraperitoneal chemoport-related adverse events. CONCLUSION:Bidirectional intraperitoneal paclitaxel with systemic S-1 plus oxaliplatin shows promising efficacy and safety in the treatment of peritoneal metastatic gastric cancer.

Purpose:Various materials and techniques have been explored to prevent anastomotic leakage (AL). Polyglycolic acid (PGA) sheets and cyanoacrylate (CA) glue have been investigated for their potential in wound healing and fistula closure. This study aims to assess the feasibility of PGA-CA complex (PCC) to prevent AL by developing a major leakage model in rats. Methods:After the creation of the major leakage model in the jejunum of rat, the leakage site was treated with each material individually and in combination. Rats were categorized into the control, CA, PGA, and PCC groups. Results:A total of 40 rats were included, with one animal from the CA and PGA groups having expired. Gross intra-abdominal conditions showed no significant difference between the groups. Median intraluminal bursting pressure was 120.0 (range, 102.5-138.0) in the CA group and 138.0 (range, 127.0-147.0) in the PCC group (P = 0.286). Pathologic evaluation revealed fibroblast activation was significantly different in the PCC group (P = 0.025). Conclusion:No significant differences were observed in the macroscopic intra-abdominal findings or intraluminal bursting pressure between the groups. The only difference in PCC group was enhanced fibroblast activation at moderate levels compare to the control group. Further research is warranted to optimize material combinations and validate efficacy in larger preclinical and clinical settings.

Background: Lymph node metastasis, particularly to extraperigastric lymph nodes, is an important issue in determining the suitability of minimally invasive treatment for early gastric cancer. However, there is a paucity of research focused on identifying risk factors for extraperigastric lymph node metastasis, which is crucial for optimizing treatment selection. Methods: Patients who underwent radical gastrectomy for early gastric cancer between 2007 and 2023 at Korea University Guro Hospital and Kyung Hee University Hospital at Gandong in Seoul, Korea, were reviewed retrospectively. We compared clinicopathologic characteristics to find out risk factors for lymph node metastasis between the no lymph node metastasis, perigastric lymph node metastasis, and extraperigastric lymph node metastasis groups. Results: A total of 1,021 patients were included in the study, with 90.0% in the lymph node metastasis, 7.94% in perigastric lymph node metastasis, and 2.06% in extraperigastric lymph node metastasis groups. Clinicopathologic analysis revealed the lymph node metastasis group exhibited a greater prevalence of mucosal lesions (55.2%), whereas the perigastric lymph node metastasis and extraperigastric lymph node metastasis groups demonstrated a greater incidence of SM3 invasion (55.6% and 52.4%, respectively; P < .001). Lymphatic invasion were found to be significantly different among the groups (P < .001). Multinomial logistic regression identified lymphatic invasion as a sole significant risk factor for the perigastric lymph node metastasis and extraperigastric lymph node metastasis groups. The 5-year relapse-free survival rates were 99.0% (lymph node metastasis), 94.5% (perigastric lymph node metastasis), and 100% (extraperigastric lymph node metastasis) (P = .011). Conclusion: This multicenter retrospective analysis indicates that lymphatic invasion is the primary independent predictor of extraperigastric lymph node metastasis in patients with early gastric cancer. Future prospective research is warranted to validate this result and establish guidelines for treatment decision-making for early gastric cancer. (c) 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Background: Even in the absence of definite evidence of pathological acid reflux, antireflux surgery (ARS) can still effectively improve gastroesophageal reflux symptoms. Nonetheless, predicting postoperative reflux symptom improvement has been primarily dependent on acid-based parameters. No objective index reflecting both acid and nonacid reflux was identified to select ARS candidates. Materials and methods: Prospectively collected data of 121 patients with gastroesophageal reflux disease (GERD), who underwent laparoscopic Nissen fundoplication from two institutions, were retrospectively reviewed. The patients reported preoperative and postoperative GERD symptoms using the Korean version of the GERD questionnaire, along with the gastroesophageal reflux disease-health-related quality of life (GERD-HRQL). The patients were assessed for reflux symptoms using bolus exposure, acid exposure time (AET), and DeMeester score (DMS) as measurements were selected. For each reflux parameter, its association, correlation, and predictive capacity of the degree of postoperative symptom resolution were analyzed using χ 2 tests, point-biserial correlations, logistic regression analyses, and receiver operating characteristic curve analyses. Results: Seventy-two patients were eligible for this study. Bolus exposure was superior to the other parameters in terms of the degree of association and correlation with a resolution of typical symptoms. Bolus exposure also showed a higher diagnostic accuracy in predicting the resolution of epigastric pain (area under the curve [AUC]=0.723, P=0.013) and regurgitation (AUC=0.981, P<0.001). Secondary analyses were performed in patients without pathological reflux, defined as the DMS-negative (DMS <14.7) or AET-negative (AET <6%) groups. In the secondary analyses, bolus exposure showed considerable diagnostic accuracy with statistical significance for all typical symptoms in both the DMS-negative (heartburn: AUC=0.717, P=0.025; epigastric pain: AUC=0.717, P=0.025; regurgitation: AUC=0.975, P<0.001) and AET-negative (heartburn: AUC=0.681, P=0.045; epigastric pain: AUC=0.749, P=0.009; regurgitation: AUC=0.975, P<0.001) groups. Conclusion: Bolus exposure, a parameter of total reflux, was superior to AET or DMS in defining candidates for ARS. Further studies investigating the surgical indications for ARS in patients with nonacid reflux using bolus exposure are required.

Purpose:To identify weight loss prediction models by validating previous models using weight loss success criteria.Materials and Methods:Patients with morbid obesity from 4 hospitals were retrospectively analyzed between Jan 2019 and 2022. Preoperative demographics, postoperative data, and 1-year follow-up weight loss outcomes were compared between 2 groups who underwent laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB). Additionally, the predictive factors for the success of excess weight loss (EWL) (>50%) and total weight loss (TWL) (>25%) were analyzed.Results:Of the 162 patients, 137 were enrolled during the study period, 75 underwent LSG, and 62 underwent LRYGB. The >50% EWL and >25% TWL 1 year after surgery were 61.3% and 43.1%, respectively. Diabetes mellitus medication use was reduced in 94.8% of patients with type 2 diabetes mellitus. Male sex and body mass index (BMI) were independent risk factors for successful weight loss (SWL) or >50% EWL (odds ratio [OR] for BMI 0.830, 95% confidence interval [CI] 0.764-0.902), whereas achieving >25% TWL was not affected by sex or BMI (OR for BMI 1.010, 95% CI 0.957-1.065). External validation of the prediction models showed an acceptable range of accuracy (adjusted R2 66.5-71.3%).Conclusion:LSG and LRYGB are feasible and effective bariatric procedures for SWL in Korean patients with morbid obesity. The TWL model was a more appropriate criterion than EWL, and weight loss prediction models may help assess the 1-year outcomes of bariatric surgery.

BACKGROUND Obesity can hinder laparoscopic procedures and impede oncological safety during laparoscopic cancer surgery. Deep neuromuscular block (NMB) reportedly improves laparoscopic surgical conditions, but its oncological benefits are unclear. We aimed to evaluate whether deep NMB improves the oncologic quality of laparoscopic cancer surgery in obese patients. STUDY DESIGN We conducted a double-blinded, parallel-group, randomized, phase 3 trial at 9 institutions in Korea. Clinical stage I and II gastric cancer patients with a BMI at or above 25 kg m -2 were eligible and randomized 1:1 ratio to the deep or moderate NMB groups, with continuous infusion of rocuronium (0.5-1.0 and 0.1-0.5 mg kg -1 h -1, respectively). The primary endpoint was the number of retrieved lymph nodes (LNs). The secondary endpoints included the surgeon's surgical rating score (SRS) and interrupted events. RESULTS Between August 2017 and July 2020, 196 patients were enrolled. Fifteen patients were excluded, and 181 patients were finally included in the study. There was no significant difference in the number of retrieved LNs between the deep (N = 88) and moderate NMB groups (N = 93; 44.6 ± 17.5 vs 41.5 ± 16.9, p = 0.239). However, deep NMB enabled retrieving more LNs in patients with a BMI at or above 28 kg/m2 than moderate NMB (49.2 ± 18.6 vs 39.2 ± 13.3, p = 0.026). Interrupted events during surgery were lower in the deep NMB group than in the moderate NMB group (21.6% vs 36.6%; p = 0.034). The SRS was not influenced by NMB depth. CONCLUSION Deep NMB provides potential oncologic benefits by retrieving more LNs in patients with BMI at or above 28 kg/m2 during laparoscopic gastrectomy.

BACKGROUND: Optimal length of biliopancreatic (BP) and Roux limb in Roux-en-Y gastric bypass (RYGB) for improved glycemic control are not known. PURPOSE: To investigate how the lengths of the BP and Roux limbs in RYGB differentially affect postoperative glycemic outcomes in patients with type 2 diabetes. DATA SOURCES: Systematic literature search using the PubMed, EMBASE, and the Cochrane Library databases. STUDY SELECTION: Studies that reported glycemic outcomes after RYGB and lengths of the BP and Roux limbs. DATA EXTRACTION: Twenty-eight articles were included for data extraction. Glycemic outcomes after RYGB were assessed using two definitions: remission and improvement. DATA SYNTHESIS: We categorized the included studies into four groups according to the BP and Roux limb lengths. The type 2 diabetes remission/improvement rates (95% confidence interval [CI]) were as follows: long BP‒long Roux group, 0.80 (0.70‒0.90)/0.81 (0.73‒0.89); long BP‒short Roux group, 0.76 (0.66‒0.87)/0.82 (0.75–0.89); short BP‒long Roux group 0.57 (0.36‒0.78)/0.64 (0.53‒0.75); short BP‒short Roux group, 0.62 (0.43‒0.80)/0.53 (0.45‒0.61). Meta-regression analysis also showed that a longer BP limb resulted in higher postoperative type 2 diabetes remission and improvement rates, whereas a longer Roux limb did not. There was no significant difference or heterogeneity in baseline characteristics, including diabetes-related variables, among the four groups. LIMITATIONS: Not all included studies were randomized controlled trials. CONCLUSIONS: Longer BP limb length led to higher rates of type 2 diabetes remission and improvement by 1 year after RYGB than the longer Roux limb length.

Background: Peritoneal carcinomatosis (PC) is the most common form of metastasis in gastric cancer (GC) and is related with a poor prognosis. Several treatment modalities including systemic chemotherapy and intraperitoneal chemotherapy have been studied and adopted in treatment of GC patients with PC. Nevertheless, few studies have reported the comparison of the oncologic outcomes between minimally invasive surgery (MIS) with intraperitoneal (IP) chemotherapy and conventional chemotherapy for GC with PC. Methods: We retrospectively reviewed the clinical records of 74 patients who had been diagnosed as GC with PC via either intra-abdominal exploration or abdominopelvic computed tomography between January 2011 and April 2021. After performing propensity score-matching for this retrospective data, we compared the outcomes of 26 patients who underwent MIS followed by IP combined systemic chemotherapy (MIS-IP group) and 26 patients who underwent systemic chemotherapy only (SC-only group). Results: The 2-year progression free survival rate of the MIS-IP group was significantly higher than the SC-only groups (36.4% and 10.5%, respectively; p = 0.010). In multivariate analysis to detect relevant factors on PFS, IP chemotherapy (HR 0.213; p < 0.001), Eastern Cooperative Oncology Group performance status (HR 3.689; p = 0.002), and the amount of ascites (p = 0.011) were significant prognostic factors. Conclusions: This study demonstrated the therapeutic potential of MIS conjoined IP plus systemic chemotherapy for GC patients with PC. MIS conjoined by IP plus systemic chemotherapy can be adopted as a treatment option to reboot the role of IP chemotherapy in GC patients with PC.

Purpose Tegafur/gimeracil/oteracil (S-1) and capecitabine plus oxaliplatin (CAPOX) are standard adjuvant chemotherapies (ACs) administered after gastrectomy to patients with stage II or III gastric cancer. However, the efficacy of AC in elderly patients remains unclear. The objective of this retrospective multicenter cohort study was to compare the efficacies of S-1 and CAPOX AC in patients aged ≥70 years. Materials and Methods Nine hundred eighty-three patients who were treated with AC using S-1 (768 patients) or CAPOX (215 patients) were enrolled in this study. Each patient underwent AC after curative gastrectomy for stage II or III gastric cancer at one of 27 hospitals in the Republic of Korea between January 2012 and December 2013. Relapse-free survival (RFS) and overall survival (OS) were analyzed according to AC regimen and age group. Results Of the 983 patients, 254 (25.8%) were elderly. This group had a similar RFS (P=0.099) but significantly poorer OS (p=0.003) compared with the non-elderly group. Subgroup analysis of the non-elderly group revealed no AC-associated differences in survival. Subgroup analysis of the elderly group revealed significantly better survival in the S-1 group than in the CAPOX group (RFS, P<0.001; OS, P<0.001). Multivariate analysis revealed that the CAPOX regimen was an independent poor prognostic factor for RFS (hazard ratio [HR], 1.891; 95% confidence interval [CI], 1.072–3.333; P=0.028) and OS (HR, 2.970; 95% CI, 1.550–5.692; P=0.001). Conclusions This multicenter observational cohort study found significant differences in RFS and OS between S-1 and CAPOX AC among patients with gastric cancer aged ≥70 years.