Resection of colorectal liver metastases: is a resection margin of 3 mm enough? : a multicenter analysis of the GAST Study Group.

Background: A safety margin of > or =10 mm is generally accepted in surgery for colorectal metastases. It is reasonable that modern methods of liver parenchyma dissection may allow for a reduction in this distance.

Methods: A total of 333 patients were included in a multicenter trial after resection of colorectal liver metastases. Dissection of the liver had been performed with a CUSA, UltraCision, or water-jet dissector. The size of the resection margin was correlated with recurrence risk and survival.

Results: The median hepatic recurrence-free survival reached 35 months for all patients; median recurrence-free survival was 24 months and overall survival was 41 months. Univariate analysis of different groups denoting the extent of resection margin (> or =10 mm, 6-9 mm, 3-5 mm, 1-2 mm, 0 mm (R1)) indicated that a margin of 1-2 mm leads to a significantly reduced median hepatic recurrence-free survival of 20 months (p = 0.004) and recurrence-free survival of 19 months (p = 0.011). Patients with R1 resection had the worst prognosis. Overall survival was not influenced by the size of the resection margin. Surgical margins were significantly reduced in simultaneous resections of four or more liver metastases and in cases in which metastatic infiltration of central liver segments was present. At multivariate analysis, resection margins of 1-2 mm and 0 mm were independent predictors of hepatic recurrence and overall recurrence.

Conclusion: The indication for resection of metastases can be safely extended to cases in which tumors sit closer than 1 cm to nonresectable structures.