Classifying the Stage IV Colorectal Cancer: Prognostic Impact of Radical Resection for Colorectal liver Metastases and Proposal for a New Staging System

Currently, there is no universally accepted system to classify the stage IV colorectal cancer. Here, we analyze the prognostic impact of radical resection for colorectal liver metastases and propose a new staging system for stage IV colorectal cancer. A retrospective review was undertaken of 126 consecutive patients who underwent surgical treatment for colorectal liver metastases from January 1997 to January 2004. Based on the overall survival rates (Kaplan–Meier method) and surgical outcomes, we propose a new staging system for stage IV colorectal cancer. Patients were divided into two groups: patients who underwent initial hepatic resections (R0 resection) for liver metastases (group 1, n = 22), and patients who underwent palliative resection for unresectable liver metastases (group 2, n = 104). The overall survival rates in group 1 at 1, 3, and 5 years were 68.2 % (15/22), 40.9 % (9/22), and 18.2 % (4/22), respectively. The overall survival rates in group 2 at 1, 3, and 5 years were 54.8 % (57/104), 16.3 % (17/104), and 0 % (0/104), respectively. There was a significant difference in overall survival rates between both groups (p < 0.05). Based on the study results, we propose a new staging system where all distant metastases are grouped within stage IV and subclassified into resectable (R0 resection) and unresectable stages. Curative surgical treatment is a critical prognostic factor in colorectal liver metastases. The proposed new staging system for stage IV colorectal cancer is simple and is clinically useful to estimate the prognosis.