583P - Pre-Op Cea Influences Interpretation of Cea Dynamics for Surveillance of Recurrent Colorectal Cancer

Abstract

ABSTRACT Background Serial serum carcinoembryonic antigen (CEA) assays are routinely performed following curative resection of colorectal cancer. The interpretation of post-op CEA dynamics in relation to pre-operative CEA values remains unclear. The aim of our study was to determine the value of pre-op CEA levels in interpreting subsequent rises in CEA for detection of recurrent disease. Methods We identified 699 patients who developed recurrent disease following curative resection of colorectal cancer. Patient's demographics, clinical and histopathologic characteristics, time to recurrence were evaluated in relation to pre-op CEA levels and CEA dynamics. Median time to recurrence was 20 months (95%CI: 27.3-35.0). Results Prior to curative surgery, 49.5% of patients had a Pre-op CEA > 5 Ug/L (primary tumor is a “secretor”) whilst 50.5% did not have elevated pre-op CEA (“non-secretor”). The pre-op CEA value is prognostic (continuous variable, p 5 Ug/L prior to relapse was observed in 51% of all patients. This new rise was more likely to be observed among patients whose initial primary was secretory (p Conclusions Pre-operative CEA levels prior to initial surgery influence CEA dynamics post curative resection in patients with recurrent colorectal cancer. Among secretors, fall to baseline CEA is associated with longer time to recurrence. Among all patients, a new rise in CEA is more likely to occur in patients whose initial primary is secretory. Once this new rise occurs, median time to recurrence is 2.4 months and this duration is not dependent on initial secretory status. Disclosure All authors have declared no conflicts of interest.