Proposal of a new and simple staging system of colorectal liver metastasis

AIM: To create a new, simple and useful staging system for colorectal liver metastasis analogous to the Tumor Node Metastasis classification system of International Union Against Cancer. METHODS: A retrospective review was undertaken of 81 consecutive patients who underwent partial hepatec- tomy for colorectal liver metastases (group 1). Clinical and pathological features of both primary and metastatic liver cancers were entered into a multivariate analysis to determine independent variables helpful in accurately predicting long-term prognosis after hepatectomy. Using selected variables, we created a new staging system like TNM classification. The usefulness of the new staging system was examined in a series of 92 patients from an- other hospital (group 2). RESULTS: Multivariate analysis showed that 81 patients in group 1 had significant multiple hepatic tumors with the largest tumor being more than 5 cm in diameter, resectable extrahepatic distant metastases, and inde- pendent prognostic factors for poor survival after hepa- tectomy. Using these three variables, we created a new staging system to classify patients with colorectal liver metastases. Finally, our new staging system classified the patients both in group 1 and in group 2. CONCLUSION: Our new staging system of colorectal liver metastasis is simple and useful for staging patients.