A new strategy for the early detection of colorectal cancer recurrence.

Abstract

416 Background: Several biological markers have been tested for colorectal cancer (CRC) including CEA; however, they are of limited use for recurrence diagnosis due to low sensitivity. Almost 50% of CRC cases experience recurrence and more than 50% of them have low values not detectable by CEA. Therefore, an effective marker for detection of recurrence will vastly increase the quality of life and survival rate. Onko-Sure is an FDA-cleared blood test that is used for the monitoring of treatment/recurrence of CRC. This ELISA assay measures the accumulation of Fibrin/Fibrinogen Degradation products in the serum using an antibody against the DR-70. The goal of this study was to determine whether the combined usage of DR-70 and CEA will improve the sensitivity for detecting recurrences. Methods: A total of 75 serum samples were retrospectively recruited through a serum bank in two arms including the confirmed healthy control (n=39) and biopsy-confirmed recurrent CRC (n=36) groups. For each patient, the serum sample was tested for DR-70 and CEA concentrations. Results: The results showed sensitivity of 75% and specificity of 58.97% for DR-70 and CEA combined. The cut points were calculated as 1.3ug/ml for DR-70, and 3 or 5ng/ml for CEA for non-smokers and smokers; respectively. For the combined analysis, if either CEA or DR-70 was positive, the test was considered positive and if both tests were negative, the result was considered negative. The sensitivity for the combined test was much better than that of each of the markers alone (35% higher than that of CEA). Conclusions: The combined usage of DR-70 and CEA in monitoring of CRC recurrence showed a significant clinical advantage in terms of sensitivity over each marker alone. Improvement in detection of recurrence has important implications to patient treatment options and prognosis. Should an IVD increase early detection of CRC recurrence when used adjunctively with other available diagnostic markers, the annual deaths due to CRC recurrence could be reduced due to the increase in early detection and the survival rate of those early detections.