Simplified staging system for predicting the prognosis of patients with resectable liver metastasis: development and validation

HYPOTHESIS: Although several staging systems for colorectal liver metastasis have been proposed, simple and generally accepted staging systems are not available for this disease. We hypothesized that more detailed analysis of primary colorectal cancer may make it possible to develop a simple staging system and that its stratification ability may be demonstrated by validation against data from unrelated patients. DESIGN: Retrospective analysis of prospectively documented data, development of a stage, and validation against an unrelated cohort. SETTING: Four tertiary referral centers. PATIENTS: Twenty-two clinicopathologic factors were examined in 369 consecutive patients who underwent curative resection for liver metastasis from colorectal cancer (original cohort). Using the independent prognostic factors, a simplified staging system was developed and was validated by data from 229 unrelated patients (validation cohort). MAIN OUTCOME MEASURES: Kaplan-Meier survival curve analyses between different prognostic groups in the cohorts. RESULTS: Multivariate analysis revealed several independent prognostic variables, including hepatic lymph node metastasis (relative risk 4.39), 4 or more colorectal lymph node metastases (RR 1.50), carcinoembryonic antigen level of 50 ng/mL or higher (RR 1.29), and multiple hepatic metastases (RR 1.27). Patients with hepatic lymph node metastasis were assigned to stage 4, and the remaining patients were divided according to number of factors: none, stage 1; 1, stage 2; 2 or 3, stage 3. In the original cohort, median survival in stages 1, 2, 3, and 4 was 7.2, 3.5, 2.0, and 1.3 years, respectively. In the validation cohort, these values were 9.6, 4.1, 2.8, and 1.6 years, respectively. CONCLUSIONS: The proposed simplified staging system was easy to use, was highly predictive of patient outcome, and permitted categorization of patients into treatment groups. Although we validated this staging system, further validation and improvements are needed.