Abstract
Abstract only
409
Background: Carcinoembryonic antigen (CEA) is a widely used tumor marker for surveillance in colon cancer. However, its accuracy is still debatable as its levels vary based on several factors. Hence we attempted to identify various clinicopathological factors influencing the CEA levels in patients with colon cancer.
Methods: Retrospective analysis of 8910 colon cancer patients from 1995 to 2008 was done via the Veteran's Affairs Central Cancer Registry. Age at diagnosis, race, gender, stage, grade, CEA levels, depth of tumor invasion, nodal status, spread of tumor, smoking history, and family history data was studied. The influence of individual factors on CEA positivity was studied by using chi-square test for categorical variables and the unpaired t-test for continuous variables.
Results: Out of 8919 patients identified, 3643 were CEA positive and 5276 were CEA negative. CEA levels varied significantly by race, stage, grade, nodal status, smoking history, and tumor size. African Americans have higher CEA levels (22% vs. 15.5%; P<0.0001). CEA positivity increased with increase in stage (stage 1- 20.3% vs. 54.3%; stage 2 – 15.8% vs.22.5%; stage 3 – 10% vs. 12%; stage 4 – 54% vs. 11.4%; P<0.0001). Increasing in T stage showed a proportionate increase in CEA positivity (T1 – 6.4% vs. 18%; T2 – 13.4% vs. 24%; T3 – 64.2% vs. 52%; T4 – 16% vs.7%; P<0.0001). Majority of CEA positive patients are node positive (N0 – 49.4% vs. 70.4%; N1- 28% vs. 20%; N2 – 22.3% vs. 10%; P<0.0001). CEA positive tumors had larger size of tumor compared to CEA negative tumors (54.2 mm vs. 45.6 mm; P<0.0001). CEA positive patients had more poorly differentiated tumors (17.5 % vs. 14.2 %; P<0.0001). Current smokers showed higher CEA levels (54% vs. 41.4%; P<0.0001). Age, gender, location of tumor and family history showed no significant difference among CEA positive and negative tumors.
Conclusions: Significant clinicopathological differences noted in CEA positive and negative tumors. African Americans had high-CEA levels and these patients had larger tumor diameter, advanced T stage, more positive nodes, advanced stage and in current smokers. Moreover, a significant difference in histologic tumor grade was observed in CEA positive and negative patient groups.