Potential Prognostic Impact of Baseline CEA Level and Surgery of Primary Tumor Among Patients with Synchronous Stage IV Colorectal Cancer: A Large Population Based Study.

Prognostic role of surgical resection of the primary tumor and baseline CEA among patients with synchronous stage IV colorectal cancer (CRC) remains an area of debate. The objective of this study was to determine the prognostic value of baseline CEA and surgical resection of the primary among patients with synchronous stage IV CRC in the era of modern chemotherapy and biologic therapy. The Surveillance, Epidemiology and End Results Registry was searched to identify patients with synchronous stage IV CRC diagnosed between 2004 and 2009. 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 patient and tumor characteristics and CCS. Three hundred thirty-three thousand, three hundred ninety nine patients were identified in the SEER registry. Median CCS among patients with their primary tumor removed was 21 M vs. 7 M (primary intact) respectively (p < 0.001). Median CCS among patients who had an elevated vs. non-elevated baseline CEA level was 14 M vs. 24 M respectively (p < 0.0001). By multivariable analysis, patients with an elevated baseline CEA had a 56 % increased risk of death from CRC compared to those with a non-elevated CEA level (HR = 1.56, 95%CI 1.47-1.65, p < 0.0001). Similarly patients who underwent surgical resection of the primary tumor had a 33 % decreased risk of death from CRC compared to those who did not (HR = 0.61, 95%CI 0.54-0.69, p < 0.0001). In our review of this large population SEER based study, an elevated baseline CEA level and surgical resection of the primary tumor among patients with synchronous stage IV CRC appeared to impact survival outcomes. Prospective validation of these results in a surgically unresectable patient population will be required.