Tumor marker CA 11-19 as a new serum blood test for monitoring colorectal cancer.

536 Background: Colorectal cancer remains the third most frequent cause of cancer deaths globally. The FOBT (fecal occult blood test) and FIT (fecal immunochemical test) as well as CEA are increasingly being used to screen or monitor patients at increased risk for colorectal cancer (CRC), however none has optimal performance in terms of both sensitivity and specificity. Data was recently published* on the new serum blood test colorectal tumor marker CA11-19. This data showed a sensitivity of 98% (95% CI, 93.1%-99.5%) and specificity of 84% (95% CI, 80.0%-87.9%) at a cut-off value of 6.5 U/mL with a high sensitivity for detection of early stage CRC as opposed to CEA whose values are reported ~40% and ~30–80%** respectively for sensitivity and specificity. This study will look at case studies that show an array of long-term monitoring outcomes which suggest possible use of CA 11-19 instead of CEA. Methods: Using a sandwich ELISA assay, a new colon cancer antigen, CA 11-19, (100 kDa glycoprotein) was measured in samples of 7 patients with a variety of conditions in normal, benign GI diseases, polyps and colon cancer. This long-term follow up is recorded from 8 to 20 years. Results: Serum samples previously frozen were used to measure the CA11-19 antigen. An average follow up time of 15 years (range 8 to 20 years) was recorded. Elevated levels of CA11-19 were detected in patients with polyps and CRC prior to treatment and decreased levels were measured after the removal of the polyps or cancer. Importantly, rising rates of CA11-19 were seen in patients with cancer recurrences of colorectal cancers. Conclusions: CA 11-19 is a serologic tumor marker for colorectal cancer with a published sensitivity of 97.7% and a specificity of 84.4%*. Preliminary reports from 7 cases show long-term data which could be more helpful in monitoring and or follow-up of high risk patients for CRC than the current CEA testing method. Additional studies are needed to further validate the use of CA 11-19 in these patient groups.