R1 Resection for Colorectal Liver Metastases: a Survey Questioning Surgeons about Its Incidence, Clinical Impact, and Management.

Background: A ≥ 1-mm margin is standard for resection of colorectal liver metastases (CLM). However, R1 resection is not rare (10-30%), and chemotherapy could mitigate its impact. The possibility of detaching CLM from vessels (R1 vascular margin) has been described. A reappraisal of R1 resection is needed.

Methods: A 19-question survey regarding R1 resection for CLM was sent to hepatobiliary surgeons worldwide. Seven clinical cases were included.

Results: In total, 276 surgeons from 52 countries completed the survey. Ninety percent reported a negative impact of R1 resection (74% local recurrence, 31% hepatic recurrence, and 36% survival), but 50% considered it sometimes required for resectability. Ninety-one percent of responders suggested that the impact of R1 resection is modulated by the response to chemotherapy and/or CLM characteristics. Half considered the risk of R1 resection to be an indication for preoperative chemotherapy in patients who otherwise underwent upfront resection, and 40% modified the chemotherapy regimen when the tumor response did not guarantee R0 resection. Nevertheless, 80% scheduled R1 resection for multiple bilobar CLM that responded to chemotherapy. Forty-five percent considered the vascular margin equivalent to R0 resection. However, for lesions in contact with the right hepatic vein, right hepatectomy remained the standard. Detachment from the vein was rarely considered (10%), but 27% considered detachment in the presence of multiple bilobar CLM.

Conclusions: A negative margin is still standard for CLM, but R1 resection is no longer just a technical error. R1 resection should be part of the modern multidisciplinary, aggressive approach to CLM.