R1 resection of colorectal liver metastasis - What is the cost of marginal resection?

Objective: The impact of resection margins on the outcome of patients with colorectal liver metastasis (CRLM) remains controversial. We evaluated the short and long-term results of R1 resection.

Methods: Between 2006 and 2016, 202 patients underwent liver resection for CRLM. R1 resection was defined as a distance of less than 1 mm between tumor cells and the transection plain. Patient and tumor characteristics, perioperative, and long-term outcomes were assessed.

Results: In 161 (79.7%) and 41 (20.3%) patients, an R0 and R1 resections were achieved, respectively. Patients that underwent an R1 resection had higher rates of disease progression while on chemotherapy (12.1% vs 5.5%, P = 0.001), need for second-line chemotherapy (17% vs 6.2%, P < 0.001), increased use of preoperative volume manipulation (14.6% vs 5.5%, P = 0.001), and inferior vena-cava involvement (21.9% vs 8.7%, P < 0.001). These patients had higher rates of major postoperative complications (19.5% vs 6.8%, P < 0.001) and reoperations (7.3% vs 2.4%, P < 0.001). Multivariate analysis demonstrated that R1 resections were not associated with decreased recurrence-free survival or overall survival.

Conclusions: Although R1 resection is associated with worse disease behavior and postoperative complications, the long-term outcome of patients following an R1 resection is non-inferior to those who underwent an R0 resection.