Titration of serum CEA, p53 antibodies and CEA-IgM complexes in 142 patients with colorectal cancer and 150 healthy blood donors.

Background: The early detection of colorectal cancer is important issue for improving the survival rate. Although fecal occult-blood testing and Carcinoembryonic antigen (CEA) in serum is widely used for noninvasive screen method, it has limited sensitivity.Methods: 142 patients with primary colorectal cancer who underwent surgery and 150 healthy volunteers were enrolled in this study. 37 of the tumors (26%) were Stage I, 34 (24%) were Stage II, 58 (41%) were Stage III, 12 (9%) were Stage IV. In each serum sample, CEA, p53 antibodies, and CEA-IgM complexes were measured.Results: The diagnostic sensitivity with CEA (cut-off: 5 ng/ml) and p53 antibodies (cut-off: 3.0 U/ml) was 48% (68/142), Stage I 16% (6/37), Stage II 56% (19/34), Stage III 53% (31/58), and Stage IV 92% (12/13), while false positive rate was 7% (10/150). Because the sensitivity of CEA-IgM (cut-off: 150 AU/ml) was low, three tests combination did not much increase the overall sensitivity.Conclusions: The sensitivity of CEA-IgM for detecting colon cancer was lower than expected from previous study. As for the specificity of p53-antibodies, because its sensitivity is preserved with cut-off at 3.0 U/ml, re-evaluation of present cut-off level (1.3 U/ml) seemed to be needed.