In an analysis of early safety outcomes in a Chinese phase III trial (RELARC) reported in The Lancet Oncology, Xu et al found similar surgical complication rates with complete mesocolic excision vs D2 dissection in patients undergoing laparoscopic colectomy for right-sided colon cancer. The complete mesocolic excision group had a lower rate of Clavien-Dindo grade III to IV complications but a higher rate of intraoperative vascular injury.
The open-label multicenter trial included 955 patients (modified intent-to-treat population) with primary adenocarcinoma located between the cecum and right third of the transverse colon and without evidence of distant metastases. Patients were randomly assigned between January 2016 and December 2019 to undergo complete mesocolic excision (n = 495) or D2 dissection (n = 500) during laparoscopic right colectomy. Central lymph nodes were dissected in complete mesocolic excision and not in D2 dissection.
The primary endpoint of the ongoing trial is 3-year disease-free survival. The current analysis is a preplanned analysis of early safety outcomes.
“Although the complete mesocolic excision procedure might increase the risk of intraoperative vascular injury, it generally seems to be safe and feasible for experienced surgeons.”— Xu et al
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Median follow-up was 30 days.
The surgical time was 163.0 minutes in the complete mesocolic excision group vs 150.5 minutes in the D2 group (P = .0002). Intraoperative blood loss was 60.1 mL vs 54.7 mL (P = .19). Perioperative blood transfusion was required in 6% vs 4% of patients.
Intraoperative complications occurred in 24 patients (5%) in the complete mesocolic excision group vs 20 patients (4%) in the D2 group (difference = 0.8%, 95% confidence interval [CI] = −1.7%–3.4%, P = .52). Among intraoperative complications, vascular injury was significantly more common in the complete mesocolic excision group, occurring in 15 patients (3%) vs 6 patients (1%; difference = 1.8%, 95% CI = 0.04%–3.6%, P = .045).
Postoperative surgical complications occurred in 97 patients (20%) in the complete mesocolic excision group vs 109 (22%) in the D2 group (difference = −2.2%, 95% confidence interval [CI] = −7.2%–2.8%, P = .39).
Clavien-Dindo grade I to II complications occurred in 91 patients (18%) vs 92 patients (18%; difference = −0.0%, 95% CI = −4.8%–4.8%, P = 1.0). Clavien-Dindo grade III to IV complications were significantly more common in the D2 group, occurring in 17 patients (3%) vs 6 patients (1%; difference = −2.2%, 95% CI = −4.1% to −0.3%, P = .022).
Median duration of hospital stay was 7 days in each group (P =.80)
No deaths occurred within 30 days in either group.
Metastases in the central lymph nodes were detected in 13 (3%) of 394 patients in the complete mesocolic excision group who underwent central lymph node biopsy; no patients had isolated metastases to central lymph nodes.
The investigators concluded, “Although the complete mesocolic excision procedure might increase the risk of intraoperative vascular injury, it generally seems to be safe and feasible for experienced surgeons.”
Yi Xiao, MD, of Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Capital Characteristic Clinical Project of Beijing and the Chinese Academy of Medical Sciences. For full disclosures of the study authors, visit thelancet.com.