Background: Omentectomy is performed widely for locally advanced gastric cancer to prevent disease recurrence. However, its clinical benefit is unknown. Methods: This retrospective cohort study compared the outcome of gastrectomy with preservation of the omentum (GPO) and gastrectomy with resection of the omentum (GRO) among patients with cT3-T4 gastric cancer who underwent gastrectomy between 2006 and 2012 in one of five participating institutions. A consensus conference identified 28 variables potentially associated with outcome after gastrectomy for the estimation of propensity scores, and propensity score matching (PSM) was undertaken to control for possible confounders. Postoperative surgical outcomes, overall survival and disease recurrence were compared between GPO and GRO. Results: A total of 1758 patients were identified, of whom 526 remained after PSM, 263 in each group. Median follow-up was 4⋅9 (i.q.r. 3⋅1-5⋅9) years in the GRO group and 5⋅0 (2⋅5-6⋅8) years in the GPO group. The incidence of postoperative complications of Clavien-Dindo grade III or more was significantly higher in the GRO group (17⋅5 versus 10⋅3 per cent; P = 0⋅016). Five-year overall survival rates were 77⋅1 per cent in the GRO group and 79⋅4 per cent in the GPO group (P = 0⋅749). There were no significant differences in recurrence rate or pattern of recurrence between the groups. Conclusion: Overall survival and disease recurrence were comparable in patients with cT3-4 gastric cancer who underwent GPO or GRO.

Objectives: Oral function management has been recognized as important strategy for preventing postoperative complications. In this historical cohort study, we focused on the patients who planed gastrectomy, and investigated the appropriate duration and frequency of preoperative oral care to prevent complications after surgery. Methods: Patients who planed surgery for gastric cancer between 2012 and 2018 were enrolled. We defined intensive oral care (IOC) as initial intervention at least three weeks before surgery and follow-up intervention within a week before surgery.As the primary outcome, the incidence of postoperative infectious complications was compared between the IOC and non-intensive oral care groups.Results: A total of 576 patients were enrolled, including 66 with IOC. The incidence of infectious complications was 2/66 (3.0%) in the IOC group and 64/510 (12.5%) in the non-intensive oral care group. After adjusting for confounding factors, patients with IOC exposure had a lower chance of developing postoperative infectious complications (odds ratio; 0.217, 0.051-0.927). Conclusions:Intensive oral care can help prevent postoperative infectious complications after gastrectomy. These findings suggest that appropriate preoperative oral care includes at least two interventions: three weeks or more before and within one week before surgery.

Aim Gastric cancer with peritoneum dissemination is intractable with surgical resection. The evaluation of the degree of dissemination using computed tomography (CT) is difficult. We focused on the amount of ascites based on CT findings and established a scaling system to predict these patients’ prognoses. Methods We extracted individual data from a population‐based cohort. Patients diagnosed with histologically proven gastric adenocarcinoma with peritoneum dissemination were enrolled. Two raters evaluated the CT images and determined the grade of ascites in each patient: grade 0 indicated no ascites in all slices; grade 1 indicated ascites detected only in the upper or lower abdominal cavity; grade 2 indicated ascites detected in both the upper and lower abdominal cavities; and grade 3 indicated ascites extending continuously from the pelvic cavity to the upper abdominal cavity. We evaluated the relationship between the ascites grade and survival time. After adjusting for other clinical factors, we calculated hazard ratios of each ascites grade. Results A total of 718 patients were enrolled. The number of patients with grades 0, 1, 2, and 3 were 303, 223, 94, and 98, respectively. The median overall survival times were 16.0, 8.7, 5.4, and 3.0 months for ascites on CT grades 0, 1, 2, and 3, respectively ( P < .001). The adjusted hazard ratios for the survival time were 1.74 (1.33‐2.26, P < .001), 3.20 (2.25‐4.57, P < .001), and 4.76 (3.16‐7.17, P < .001) for grades 1, 2, and 3, respectively. Conclusion We established a new grading system of pretreatment ascites to better predict the prognosis of gastric cancer.