Lymph node mapping-based optimal bowel-resection margin and central radicality in colon cancer surgery: an international, prospective, observational cohort study

Abstract

Background: Substantial variations in the extent of lymphadenectomy are acknowledged internationally in colon cancer surgery because essential data for standardization, including the anatomical distribution of metastatic lymph nodes (LN), are lacking. Materials and methods: Pre-specified LN mappings based on in vivo bowel measurements were conducted for stages I-III colon cancer patients treated at 31 leading hospitals in six countries. The extent of lymphadenectomy was classified from levels A (pericolic) to C (central LNs) according to the pre-specified anatomical landmarks. The primary outcome was the extent of pericolic lymphatic spread and the incidence of metastasis in central LNs, and secondary ones included the real-world status of central radicality and its association with short-term outcomes. Results: Among 3647 patients, pericolic spread beyond 10 cm (0.2%) and absence of feeding arteries supplying the bowel within 10 cm from the primary tumor (0.3%) were rare, irrespective of nationality. The incidence of metastasis in central LNs was <^>3% (range: 0.2% in T1 to 7% in T4 tumors) and was lower in tumors located at the splenic flexure (0.5%). The proportion of patients with level C radicality was <^>76%, which was statistically significantly associated with T stage only in one country. A higher radicality level conferred no adverse impact on either the incidence of Clavien-Dindo grade >= III or 30-day mortality.