Purpose: To develop a tool for predicting survival after liver resection for patients with stage IV colorectal cancer. By using a nomogram we are trying to improve on the current practice of using prognostic scores for evaluating risks of therapeutic failure.
Patients and methods: All patients admitted to Memorial Sloan-Kettering Cancer Center (MSKCC) for curative intent for treatment of metastatic disease from colorectal cancer between January 1986 and December 1999 were included. A nomogram was developed as a graphical representation of a Cox proportional hazards regression model. The nomogram was verified for discrimination and calibration, both employing bootstrapping to obtain relatively unbiased estimates.
Results: Using nodal status of the primary tumor, disease-free interval, size of the largest metastatic tumor, preoperative carcinoembryonic antigen, bilateral resection, extensive resection (lobectomy or more), gender, number of hepatic tumors, primary cancer site (colon vs. rectum), and age, the nomogram achieved a concordance index of 0.61, statistically significantly greater than chance. The nomogram also had very good calibration.
Conclusion: This nomogram is a predictive tool, upon external validation, that can routinely be used to counsel patients in making treatment decisions. The discriminatory ability of the nomogram indicates that this population should not be considered homogeneous with respect to risk of death.