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Influence of resection margin on survival in hepatic resections for colorectal liver metastases.

BACKGROUND
Traditionally a 1-cm margin has been accepted as the gold standard for resection of colorectal liver metastases. Evidence is emerging that a lesser margin may provide equally acceptable outcomes, but a critical margin, below which recurrence is higher and survival poorer, has not been universally agreed. In a recent publication, we reported peri-operative morbidity and clear margin as the two independent prognostic factors. The aim of the current study was to further analyse the effect of the width of the surgical margin on patient survival to determine whether a margin of 1 mm is adequate.


METHODS
Two hundred and sixty-one consecutive primary liver resections for colorectal metastases were analysed from 1992 to 2007. The resection margins were assessed by microscopic examination of paraffin sections. The initial analysis was performed on five groups according to the resection margins: involved margin, 0-1 mm, >1-<4 mm, 4-<10 mm and > or = 10 mm. Subsequent analysis was based on two groups: margin <1 mm and >1 mm.


RESULTS
With a median follow-up of 4.7 years, the overall 5-year patient and disease-free survival were 38% and 22%, respectively. There was no significant difference in patient- or disease-free survival between the three groups with resection margins >1 mm. When a comparison was made between patients with resection margins < or = 1 mm and patients with resection margins >1 mm, there was a significant 5-year patient survival difference of 25% versus 43% (P < 0.04). However, the disease-free survival difference did not reach statistical significance (P = 0.14).


CONCLUSIONS
In this cohort of patients, we have demonstrated that a resection margin of greater than 1 mm is associated with significantly improved 5-year overall survival, compared with involved margins or margins less than or equal to 1 mm. The possible beneficial effect of greater margins beyond 1 mm could not be demonstrated.