External validation of two nomograms for predicting patient survival after hepatic resection for metastatic colorectal cancer.

Background: Two nomograms are available for predicting patient survival after hepatic resection for metastatic colorectal cancer (CRC). However, they have not been externally validated using other databases, and so their universal applicability has not been established. We aimed to examine the validity of these nomograms for predicting patient survival after hepatic resection for metastatic CRC in different institutions.

Methods: We analyzed the cases of 113 patients who underwent hepatic resection for metastatic CRC at Hiroshima University Hospital between 1995 and 2006. In this patient set, we assessed the predictive value of the Kattan nomogram of the Memorial Sloan-Kettering Cancer Center (MSKCC) (United States) and the Kanemitsu nomogram from the Aichi Cancer Center (Japan). The concordance index was used as an accuracy measure for comparing these two nomograms. The predictive accuracy of these nomograms was compared with that of conventional predictive models.

Results: The 3-, 5-, and 10-year overall survival rates in our cohort were 66.3%, 52.4%, and 42.7%, respectively. The concordance indexes of the pre- and postoperative Kanemitsu nomogram and that of the Kattan nomogram were 0.70, 0.69, and 0.68, respectively. These values were higher than those obtained using other models for hepatic metastatic CRC, including the clinical risk score of the MSKCC and the grading system of the Japanese Society for Cancer of the Colon and Rectum.

Conclusions: The high predictive accuracy of both nomograms shows that these predictive tools can be used in different institutions. Patient counseling and adjuvant therapy decision-making should benefit from use of these nomograms.