Recurrence patterns and their effects on clinical outcomes after R1 resection of colorectal liver metastases: a propensity score-matched analysis

Purpose The prognostic significance of the surgical margin status remains controversial for patients who undergo hepatectomy for colorectal liver metastases. This study evaluated the influence of R1 resection on recurrence patterns and prognosis in these patients. Methods Between January 2001 and December 2016, 232 consecutive Japanese patients underwent initial hepatic resection for colorectal liver metastases. Their medical records were reviewed to evaluate recurrence and survival outcomes. Results Relative to patients with R0 resection, patients with R1 resection had significantly poorer recurrence-free survival (RFS) and overall survival (OS). However, after propensity score matching, there were no significant differences in RFS and OS associated with the margin status. Nevertheless, R1 resection was associated with a significantly higher incidence of intrahepatic recurrence and early recurrence, while R0 resection was associated with a significantly higher re-resection rate for hepatic recurrence. Only eight of 55 patients with R1 resection developed recurrence at the R1 resection margin, whereas 36 patients developed recurrence at other sites/organs. Conclusion Among patients with similar characteristics, R1 resection does not affect long-term outcomes. This suggests that R1 resection itself is not a cause of a poor prognosis, but rather a potent indicator of aggressive tumor biology.