Detailed pathologic characteristics of the primary colorectal tumor independently predict outcome after hepatectomy for metastases.

INTRODUCTION: Outcome after hepatic resection for colorectal cancer liver metastases (CRLM) is heterogeneous and accurate predictors of survival are lacking. This study analyzes the prognostic relevance of pathologic details of the primary colorectal tumor in patients undergoing hepatic resection for CRLM.

METHODS: Retrospective review of a prospective database identified patients who underwent resection for CRLM. Clinicopathological variables were investigated and their association with outcome was analyzed.

RESULTS: From 1997-2007, 1,004 patients underwent hepatic resection for CRLM. The median follow-up was 59 months with a 5-year survival of 47%. Univariate analysis identified nine factors associated with poor survival; three of these related to the primary tumor: lymphovascular invasion (LVI, p<0.0001), perineural invasion (p=0.005), and degree of regional lymph node involvement (N0 vs. N1 vs. N2, p<0.0001). Multivariate analysis identified seven factors associated with poor survival, two of which related to the primary tumor: LVI (hazard ratio (HR) 1.3, 95% confidence interval (CI) 1.06-1.64, p=0.01) and degree of regional lymph node involvement [N1 (HR 1.3, 95% CI 1.04-1.69, p=0.02) vs. N2 (HR 1.7, 95% CI 1.27-2.21, p<0.0005)]. A significant decrease in survival along the spectrum of patients ranging from LVI negative/N0 to LVI positive/N2 was present. Patients who were LVI-positive/N2 had a median survival of 40 months compared with 74 months for patients who were LVI-negative/NO (p<0.0001).

CONCLUSIONS: Histopathologic details of the primary colorectal tumor, particularly LVI and the detailed assessment of the degree of lymph node involvement, are strong predictors of survival. Future biomarker studies should consider exploring factors related to the primary colorectal tumor.