Biological characteristics and behaviour of putatively curatively resected colorectal liver metastases

To identify whether positive resection margin tumours had a more aggressive phenotype, using tumour micro-vessel density and invasive margin.Archival tissue was retrieved from 109 patients who had undergone resection for colorectal liver metastases. The nature of the invasive margin was determined by HE histochemistry. MVD was visualised using immunohistochemical detection of CD31 antigen and quantified using image capture computer software. Clinical details and outcome were retrieved and collated with invasive margin and MVD data in a statistical database.41/68 patients with a positive resection margin (R1) had recurrences following liver resection, while only 16/41 patients with a clear margin (R0) developed recurrences. More of the margin clear patients also developed capsulated liver metastases (56%), compared to positive resection margin patients (22%) (Chi squared test p0.001). The stromal margin MVD in the R0 patients was 250 (11-609), compared to the R1 value of 122 (27-428) (Mann-Whitney U test p=0.01).Positive resection margin, amongst other factors, is a predictor of poor prognosis. This appears to be in part explained by the expression of adverse tumour characteristics.