We examined which, and how many, mucin markers are necessary to define the phenotypes of gastric cancers, and re-evaluated the incidence of their mucin phenotypes and whether minute gastric carcinomas arise as unclassified type. Well-differentiated-type minute gastric carcinomas (n = 33) measuring 0%, and was 33%, 33%, 3%, 30%, and 0%, respectively, when the percentage of positive mucin phenotype was set at >or=10%. Thus, a panel of MUC5AC (or HGM), MUC6, MUC2 and CD10 stains is indispensable for accurately determining the mucin phenotypes of gastric carcinomas, and the above-mentioned classification is important for studying changes in the histological types of well-differentiated-type adenocarcinomas during change to the poorly differentiated type, as well as corresponding genetic abnormalities.

In Japan, the first endoscopic surgery, a laparoscopic cholecystectomy, was performed in 1990. Since then, operative procedures have been standardized, and the safety and efficacy of endoscopic surgery have been evaluated. In accordance with the social acceptance of endoscopic surgery as a less invasive type of surgery, the number of endoscopic procedures performed has increased in all surgical domains. The Japan Society for Endoscopic Surgery (JSES) has played an important role in the development of endoscopic surgery in Japan. Notably, a technical skills certification system for surgeons was established by the JSES to train instructors on how to teach safe endoscopic surgery. Furthermore, the JSES has conducted a national survey every two years to evaluate the status of endoscopic surgery over time. In 2017, 248 743 patients underwent endoscopic surgery in all surgical domains, such as abdominal, thoracic, mammary and thyroid gland, cardiovascular, obstetrics and gynecology, urologic, orthopedic, and plastic surgery. The 14th National Survey of Endoscopic Surgery conducted by the JSES demonstrated the status of laparoscopic surgery in Japan in 2016‐2017.

LDG offers particular advantages to elderly patients with early gastric cancer, including rapid return of gastrointestinal function, fewer complications and a shorter hospital stay.

Aim This study aimed to evaluate the association between surgeons certified via the Endoscopic Surgical Skill Qualification System (ESSQS) of the Japan Society for Endoscopic Surgery (JSES) and surgical outcomes of laparoscopic distal gastrectomy (LDG) and laparoscopic low anterior resection (LLAR). Methods Japanese National Clinical Database data on the patients undergoing LDG and LLAR between 2014‐2016 were analyzed retrospectively. The proportion of cases performed by ESSQS‐certified surgeons was calculated for each procedure, and clinicopathological factors with or without participation of ESSQS‐certified surgeons as an operator were assessed. Then, effects of operations performed by ESSQS‐certified surgeons on short‐term patient outcomes were analyzed using generalized estimating equations logistic regression analysis. Results There were 110 610 and 65 717 patients who underwent LDG and LLAR, respectively. The operations performed by ESSQS‐certified surgeons in each procedure totaled 28 467 (35.3%) and 12 866 (31.2%), respectively. A multivariable logistic regression model showed that odds ratios of mortality for LDG and LLAR performed by ESSQS‐certified surgeons were 0.774 (95% CI, 0.566‐1.060, P = 0.108) and 0.977 (0.591‐1.301, P = 0.514), respectively. Odds ratios for secondary endpoints of anastomotic leakage in LDG and LLAR performed by ESSQS‐certified surgeons were 0.835 (95% CI, 0.723‐0.964, P = 0.014) and 0.929 (0.860‐1.003, P = 0.059), respectively, whereas that of ileus/bowel obstruction for LLAR performed by ESSQS‐certified surgeons was 1.265 (1.132‐1.415, P < 0.001). There were no significant associations between the two operations performed by ESSQS‐certified surgeons and other factors such as mortality and overall complications. Conclusions ESSQS certification did not affect postoperative mortality following LDG and LLAR, but annual experience of laparoscopic surgery was associated with it. ESSQS certification may contribute to favorable outcomes regarding anastomotic leakage following LDG and LLAR.