Background: Prior to curative surgery for colon cancer, carcinoembryonic antigen (CEA) has been reported to be a poor prognostic factor recommended for routine measurement, however the majority of studies evaluating this have not adjusted for the preoperative systemic inflammatory response (SIR) –widely shown to be associated with worse outcomes. The present study aims to analyse the association between preoperative CEA and long-term outcomes when adjusted for other factors including Systemic Inflammatory Grade (SIG). Methods: The effect on overall/cancer specific survival (OS/CSS) of preoperative CEA (<5/5+) was examined in a regional cohort of patients undergoing surgery for colon cancer after adjustment for other clinicopathological factors including the SIR as measured by Systemic Inflammatory Grade (SIG). Results: 624 patients were identified undergoing curative surgery for colon cancer with a preoperative CEA available. For 3-year OS stratified by TNM Stage, CEA offered further prognostic value in patients with TNM Stage I (98% vs 75%, p=0.002), but not Stage II (p=0.444) or Stage III (p=0.351) disease. For 3-year OS stratified by SIG, CEA did not add further significant prognostic value for any SIG (all p>0.05). On multivariate analysis, age (HR 1.65, p=0.020), sex (HR 0.53, p=0.001), mode of presentation (HR 1.93, p=0.008), TNM Stage (HR 1.83, p<0.001) and SIG (HR 1.30, p<0.001) remained significant for OS, but not CEA (p=0.620). Conclusions: The present results show that there is limited prognostic value of preoperative CEA. The SIR as measured by SIG should be routinely measured prior to curative colonic surgery. A mandatory reporting dataset is required in colorectal cancer and should include SIG.