Meta-analysis finds R1 vascular margin acceptable for HCC but not CLM in minimally invasive liver surgery

BACKGROUND: The concept of tumor-vessel detachment (R1 vascular [R1v]), has recently gained attention within the minimally invasive (MI) setting, but its oncological adequacy remains poorly defined. This meta-analysis aims to assess the outcomes of MI-R1v hepatectomy for hepatocellular carcinoma (HCC) and colorectal liver metastases (CLM). PATIENTS AND METHODS: A literature search was conducted in MEDLINE, Embase, and Cochrane Library to identify studies reporting local recurrence (LR) rates following MI-R1v for HCC and CLM. Secondary outcomes included the extent of hepatectomy (major versus parenchyma-sparing), tumor burden (monofocal versus multifocal), intrahepatic recurrence, and overall survival (OS). RESULTS: In total, eight studies comprising 839 patients (410 HCC and 429 CLM) were included. In HCC, LR rates were comparable between R1v and R0 (5.6% versus 7.9%; odds ratio [OR] 1.2, 95% confidence interval [CI] 0.25-6.1; p = 0.79), whereas in CLM, LR was higher after R1v (12.3% versus 6.4%; OR 3.4, 95% CI 1.10-10.54; p = 0.03). Robotic and laparoscopic R1v resections showed similar LR rates in both HCC (2.8% versus 4.8%; p = 0.82) and CLM (15% versus 12%; p = 0.08). No significant differences were observed between MI-R1v and MI-R0 resections in terms of extent of hepatectomy, tumor burden, intrahepatic recurrence, or OS in either group. CONCLUSIONS: The comparable LR rates suggest that the R1v approach is oncologically acceptable for HCC in the MI setting, supporting its use when R0 cannot be achieved without a major hepatectomy. The higher LR rates in R1v for CLM resections require cautious patient selection and further standardization. Prospective studies are needed to define clear oncological benchmarks for MI-R1v procedures.