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)

BACKGROUND: Institutional variation in outcomes is a key factor to ascertain the generalizability of results and reliability of the clinical trial. This study evaluated institutional variation in survival and postoperative complications using data from JCOG0404 comparing laparoscopic colectomy (LAP) with open colectomy (OP). METHODS: Institutions with fewer than 10 registered patients were excluded from this analysis. Institutional variation was evaluated in terms of early postoperative complications, overall survival, and relapse‐free survival and estimated using a mixed‐effect model with institution as a random effect after adjusting for background factors. RESULTS: This analysis included 1028 patients in the safety analysis and 1040 patients in the efficacy analysis from 26 institutions. In the safety analysis, there was no variation in grades 3–4 early postoperative complications (in OP, median 6.3% [range 6.3%–6.3%]; in LAP, median 2.6% [range 2.6%–2.6%]), but some variation in grades 1–4 early postoperative complications was observed (in OP, median 20.8% [range 13.2%–31.8%]; in LAP, median 11.9% [range 7.2%–28.7%]), and that in grades 2–4 was observed only in LAP (median 8.8% [range 4.7%–24.0%]; in OP, median 12.7% [range 12.7%–12.7%]). Two specific institutions showed especially high incidences of postoperative complications in LAP. In the efficacy analysis, there was no institutional variation in OP, although a certain variation was observed in LAP. CONCLUSIONS: Some institutional variations in safety and efficacy were observed, although only in LAP. We conclude that a qualification system, including training and education, is needed when new surgical techniques such as laparoscopic surgery are introduced in clinical practice.