Katayama H, Inomata M, Mizusawa J, Nakamura K, Watanabe M, Akagi T, et al. Institutional variation in survival and morbidity in laparoscopic surgery for colon cancer: From the data of a randomized controlled trial comparing open and laparoscopic surgery (JCOG0404). Annals gastroenterological Surg. 2021;5(6):823–31.

Article  Google Scholar 

Kuhry E, Bonjer HJ, Haglind E, Hop WC, Veldkamp R, Cuesta MA, et al. Impact of hospital case volume on short-term outcome after laparoscopic operation for colonic cancer. Surg Endosc. 2005;19(5):687–92.

Article  CAS  PubMed  Google Scholar 

Chaudhary MA, Shah AA, Zogg CK, Changoor N, Chao G, Nitzschke S, et al. Differences in rural and urban outcomes: a national inspection of emergency general surgery patients. J Surg Res. 2017;218:277–84.

Article  PubMed  Google Scholar 

Hasegawa H, Takahashi A, Kakeji Y, Ueno H, Eguchi S, Endo I, et al. Surgical outcomes of gastroenterological surgery in Japan: Report of the National Clinical Database 2011–2017. Annals gastroenterological Surg. 2019;3(4):426–50.

Akagi T, Endo H, Inomata M, Yamamoto H, Mori T, Kojima K, et al. Clinical impact of Endoscopic Surgical Skill Qualification System (ESSQS) by Japan Society for Endoscopic Surgery (JSES) for laparoscopic distal gastrectomy and low anterior resection based on the National Clinical Database (NCD) registry. Annals gastroenterological Surg. 2020;4(6):721–34.

Article  Google Scholar 

Aoyama S, Inoue Y, Ohki T, Itabashi M, Yamamoto M. Usefulness of the endoscopic surgical skill qualification system in laparoscopic colorectal surgery: short-term outcomes: a single-center and retrospective analysis. BMC Surg. 2019;19(1):90.

O’Connell RM, Abd Elwahab S, Mealy K. The impact of hospital grade, hospital-volume, and surgeon-volume on outcomes for adults undergoing appendicectomy. The surgeon : journal of the Royal Colleges of Surgeons of Edinburgh and Ireland. 2020;18(5):280-6.

Kido M, Arita T, Shoda K, Shimizu H, Kiuchi J, Nanishi K, et al. Inter-prefectural and urban-rural regional disparities in rectal cancer and rectal resections: A Japanese nationwide population-based cohort study from 2014 to 2019. Annals gastroenterological Surg. 2025;9(2):281–7.

Article  Google Scholar 

Otsubo T, Kobayashi S, Sano K, Misawa T, Katagiri S, Nakayama H, et al. A nationwide certification system to increase the safety of highly advanced hepatobiliary-pancreatic surgery. J Hepato-Biliary-Pancreat Sci. 2023;30(1):60–71.

Article  Google Scholar 

Sakai Y, Kitano S. Practice Guidelines on Endoscopic Surgery for qualified surgeons by the Endoscopic Surgical Skill Qualification System. Asian J Endosc Surg. 2015;8(2):103–13.

Article  PubMed  Google Scholar 

Kazama K, Numata M, Aoyama T, Atsumi Y, Tamagawa H, Godai T, et al. Does the Endoscopic Surgical Skill Qualification System improve patients’ outcome following laparoscopic surgery for colon cancer? A multicentre, retrospective analysis with propensity score matching. World J Surg Oncol. 2021;19(1):53.

Baba H. National Clinical Database (NCD) in Japan: Clinical and social significance. Ann Gastroenterol Surg. 2019;3(5):462–3.

Article  PubMed  PubMed Central  Google Scholar 

Kakeji Y, Yamamoto H, Ueno H, Eguchi S, Sasaki A, Takiguchi S, et al. Development of gastroenterological surgery over the last decade in Japan: analysis of the National Clinical Database. Surg Today. 2021;51(2):187 − 93.

Yamamoto T, Takahashi A, Yoshizumi T, Ishihara S, Inomata M, Imoto S et al. 2023 National Clinical Database Annual Report by the Japan Surgical Society. Surg Today. 2025;55(3):295–334.

Fujii S, Akagi T, Inomata M, Katayama H, Mizusawa J, Ota M, et al. Transitional impact of short- and long-term outcomes of a randomized controlled trial to evaluate laparoscopic versus open surgery for colorectal cancer from Japan Clinical Oncology Group Study JCOG0404. Annals gastroenterological Surg. 2019;3(3):301–9.

Article  Google Scholar 

Ono R, Nonaka T, Tominaga T, Ishii M, Hisanaga M, Araki M, et al. Effect of endoscopic surgical skill qualification system for laparoscopic rectal surgery: Japanese multicenter analysis. Surg Endosc. 2025;39(1):394–400.

Article  PubMed  Google Scholar 

Katayama H, Tominaga T, Nonaka T, Wada H, To K, Hamada K, et al. Effect of endoscopic surgical skill qualification system for laparoscopic multivisceral resection: Japanese multicenter analysis. Surg Endosc. 2022;36(5):3068–75.

Article  PubMed  Google Scholar 

Ishii M, Tominaga T, Nonaka T, Takamura Y, Oishi K, Hashimoto S, et al. Comparison of robotic and laparoscopic approaches in short- and long-term outcomes of lateral pelvic lymph node dissection for advanced rectal cancer: a Japanese multicenter study. Langenbecks Arch Surg. 2024;410(1):18.

Article  PubMed  Google Scholar 

Nanashima A, Hidaka S, Nonaka T, Yamasaki N, Tsuchiya T, Matsumoto K, et al. Recruitment of Young Medical Apprentices (RYOMA) project: a comprehensive surgical education program at a local academic institute in Japan. J Surg Educ. 2014;71(4):587–92.

Article  PubMed  Google Scholar 

Takamura Y, Tominaga T, Nonaka T, Oishi K, Noda K, Hashimoto S, et al. Impact of institutional volume on short- and long-term outcomes after laparoscopic colectomy. Asian J Endosc Surg. 2024;17(2):e13295.

Tominaga T, Nonaka T, Hashimoto Y, Hamasaki K, Arai J, Matsumoto K et al. A surgical training system designed to help trainees acquire laparoscopic surgical skills at a rural Japanese institute. Surg Today. 2023.