Nonmicroradical Resection Margin as a Predictor of Recurrence in Patients With Stage III Colon Cancer Undergoing Complete Mesocolic Excision: A Prospective Cohort Study

BACKGROUND: The prognostic value of the present definition of microradicality in colon cancer is poorly understood, especially considering the vast influence it has in rectal cancer prognosis. OBJECTIVE: This study aimed to investigate whether the risk of recurrence after complete mesocolic excision for stage III colon cancer is associated with the distance from tumor tissue to resection margin and whether the location of the involved margin is of any significance. DESIGN: A prospective cohort of patients was stratified into 2 groups to distinguish between direct margin invasion (0-mm resection margin) and a <= 1-mm resection margin without direct invasion or 3 groups to distinguish between the location of margin involvement (lateral tumor resection margin, central vascular ligation margin, and nonperitonealized mesocolic resection margin). Patients with microradical resections were used as a control group. SETTINGS: We included all patients undergoing elective complete mesocolic excision for International Union Against Cancer stage III colon cancer at Nordsjaellands Hospital between January 1, 2008, and December 31, 2016. PATIENTS: A total of 276 patients met all inclusion criteria and none of the exclusion criteria. MAIN OUTCOME MEASURES: Primary outcome was risk of recurrence after 3.2 years. RESULTS: A total of 41 patients (15%) had a nonmicroradical resection. The 3.2-year cumulative incidence of recurrence for a 0-mm margin was 43% and 24% for a <= 1-mm margin without direct invasion, corresponding with an HR of 4.3 (p = 0.0146) and 1.3 (p = 0.474). The location of the involved margin showed no significant differences. LIMITATIONS: This was a single-center study containing a limited number of patients with a nonmicroradical resection with a risk of type II error. CONCLUSIONS: We found no increased risk of recurrence for a <= 1-mm margin without direct invasion, indicating that the present classification of microradicality might not be justified if an intact posterior mesocolic fascia without invasion of tumor tissue is present.