Serum specimens were obtained from 522 colonoscopy-confirmed subjects in institutional review board–approved studies. Specimens were blind coded. CA11-19 levels were determined by using enzyme-linked immunosorbent assay analysis. The results were tabulated for categories of normal, hyperplastic polyps, benign GI, adenomatous polyps, and CRC based on their final diagnosis.
When a cutoff of 6.4 units/mL for normal is used, the CA11-19 level was elevated in 128 of 131 of CRC subjects, for an observed sensitivity of 98% (95% confidence interval, 93.1%-99.5%). Normal levels were found in 87% of normal subjects (90/103) and 83% of those with benign GI diseases (185/223). When combined, this yields an observed specificity of 84% (95% confidence interval, 80.0%-87.9%).
CA11-19 is a serologic tumor marker for the diagnosis of CRC with a sensitivity of 98% and specificity of 84%. This high sensitivity means that this test will detect 43 of 44 cases of CRC presented. For those older than 50 years of age, it has a positive predictive value of 3.6% and a negative predictive value of 99.98%. Additional prospective studies are needed to further clarify the use of CA11-19 as an aid in the diagnosis of CRC.