Bergein F. Overholt, MD, from Gastrointestinal Associates in Knoxville, Tennessee, USA describes this Original Article, “CA11-19: a tumor marker for the detection of colorectal cancer.”

This study details clinical results of CA 11-19, a new serum tumor marker, for the diagnosis of colorectal cancer (CRC). Results demonstrate a sensitivity of 98% and specificity of 84% for the diagnosis of CRC. The test is highly sensitive for detection of stages I – III CRC.

Early detection of colon cancer is key to improving survival rates as over 90% of patients diagnosed with early stage colorectal cancer live 5 or more years after treatment. Screening procedures are key to an earlier diagnosis. A highly accurate blood test that would reliably detect colorectal cancer would be a significant advance in the diagnosis of the disease.

Figure 1. Histograms of the CA11-19 assay values for 522 subjects.

In this study, 522 colonoscopy confirmed patients were categorized into Normal, Hyperplastic Polyps, Benign GI, Adenomatous Polyps, and CRC groups based on their final diagnosis. CA11-19 levels were determined using ELISA analysis. CA 11-19 was positive (>6.5) in 128 of 131 of CRC cases for an observed sensitivity of 98%. CA 11-19 was positive in 100% of patients with stages I, II and III of colon cancer. Negative results were found in 87% of normals (90/103) and 83% of benign GI diseases (185/223). When combined, this yields an observed specificity of 84%.

Diagnostically, a positive assay result increases the odds of finding CRC by a factor of 6. A negative test reduces the likelihood of finding CRC by a factor of 17.

Stated differently, for men over 50, only about 1 in 2000 negative assay results will be a false negative. For women over 50 only about 1 in 2600 negative assay results will be a false negative. Thus, for the target demographic group, a negative assay is strong evidence that an individual is unlikely to have colorectal carcinoma.

Additional multicenter studies are required to validate this work. If further studies corroborate the findings presented in our article, a blood test that allows screening and diagnosis of CRC is near.

Find the abstract for this article online.

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