Prognostic impact of baseline CEA level and surgery of primary tumor among patients with stage IV denovo colon cancer.

Abstract

503 Background: Surgical resection of primary tumor among pts with stageIV denovo colorectal cancer is controversial. Prognostic role of baseline CEA level in the same cohort has yet to be defined. The objective of this study was to determine the prognostic value of CEA and surgical resection of primary tumor among pts with stage IV denovo colorectal cancer in the era of biologic therapy and to determine subgroups with improved survival outcome. Methods: The Surveillance, Epidemiology and End Results Registry was searched to identify patients with stage IV denovo colorectal cancer diagnosed between 2004-2007. Colorectal cancer specific survival (CCS) was estimated using the Kaplan-Meier product limit method. Cox models were fitted to assess the multivariable relationship of various pt and tumor characteristics and CCS. Results: 19,437 pts were identified with stage IV denovo colorectal cancer. Median CCS was 15M. Median CCS among pts with primary tumor removed was 20M vs 8M (primary intact; p<0.001). Median CCS among pts who had elevated vs. non elevated CEA was 14M vs 23M (p<0.0001). Among pts who had primary tumor surgery median CCS among pts who had elevated vs. non elevated CEA was 19M vs 29M (p<0.0001). Among pts who had primary tumor and distant disease surgically removed, the median CCS among pts who had elevated vs. non elevated CEA was 24M vs 35M (p<0.0001). By multivariable analysis, pts with elevated CEA had a 51% increased risk of death from colorectal cancer compared to those with a non elevated CEA level (HR=1.51, 95%CI 1.40-1.65, p<0.0001). Pts who underwent primary tumor surgery had a 33% decreased risk of death from colorectal cancer compared to those who did not (HR=0.67, 95%CI 0.58-0.78, p<0.0001). Other factors significantly associated with a decreased risk of death from colorectal cancer included low grade disease, non visceral metastases, surgical resection of metastases, younger age and white race. Conclusions: In this large population study, elevated baseline CEA level and surgical resection of the primary tumor had a significant impact on survival outcomes. The best prognostic group were those pts with normal baseline CEA level who proceeded to surgical resection for their primary tumor. No significant financial relationships to disclose.