Abstract
BACKGROUND: The modified complete mesocolic excision (mCME) procedure for right-sided colon cancer is a tailored approach based on the original complete mesocolic excision (CME) methodology. Limited studies evaluated the safety and feasibility of laparoscopic mCME using objective surgical quality assessments in patients with right colon cancer. The objectives of the PIONEER study were to evaluate oncologic outcomes after laparoscopic mCME and to identify optimal clinically relevant endpoints and values for standardizing laparoscopic right colon cancer surgery based on short-term outcomes of procedures performed by expert laparoscopic surgeons. MATERIALS AND METHODS: This is an ongoing prospective, multi-institutional, single-arm study conducted at five tertiary colorectal cancer centers in South Korea. Study registrants included 250 patients scheduled for laparoscopic mCME with right-sided colon adenocarcinoma (from the appendix to the proximal half of the transverse colon). The primary endpoint was 3-year disease-free survival. Secondary outcomes included 3-year overall survival, incidence of morbidity in the first 4 weeks postoperatively, completeness of mCME, central radicality, and distribution of metastatic lymph nodes. Survival data will be available after the final follow-up date (June 2024). RESULTS: The postoperative complication rate was 12.9%, with a major complication rate of 2.7%. In 87% of patients, central radicality was achieved with dissection at or beyond the level of complete exposure of the superior mesenteric vein. Mesocolic plane resection with an intact mesocolon was achieved in 75.9% of patients, as assessed through photographs. Metastatic lymph node distribution varied by tumor location and extent. Seven optimal clinically relevant endpoints and values were identified based on the analysis of complications in low-risk patients. CONCLUSIONS: Laparoscopic mCME for right-sided colon cancer produced favorable short-term postoperative outcomes. The identified optimal clinically relevant endpoints and values can serve as a reference for evaluating surgical performance of this procedure.