138 O - Detection of colorectal carcinoma metastases in blood

Abstract

Metastasis is an important factor that determines the prognosis of patients with cancer. A non-invasive method for the early detection of disseminating disease would provide an important predictive tool with respect to recurrence and to result in a more appropriate selection of patients for adjuvant therapy. We have used a combination of immunomagnetic separation to isolate epithelial cells from whole blood and detection by nested RT-PCR. Monoclonal antibody BerEP4, which recognizes an epitope expressed by epithelial cells, was covalently linked to magnetic beads. The RT-PCR was performed with oligonucleotides derived from the sequence of the keratin 19 gene. Serial dilutions of SW620 tumor cells were performed in normal blood. We were able to detect 1 colorectal carcinoma cell in 1 ml of whole blood. The clinical applicability of this technique was documented by evaluating patients with a colorectal carcinoma. Two patients presenting a tumor no deeper than the submucosa (stage A) were tested. None of them bad epithelial cells in their blood. For 2 out of the 8 patients who had no detected node involvement (stage B) we were able to early identify a disseminating disease. These patients may thus be at high risk of relapse. Eight patients with histologic evidence of locoregional lymph node involvement were analyzed. Six of them had detectable epithelial tumor cells in their blood. This shows that, in addition to lymph node metastases, the majority of these patients have potential distant metastases in their blood. Finally, we have analyzed 5 stage D patients. Four of them had circulating epithelial tumor cells in their blood. Metastasis is an important factor that determines the prognosis of patients with cancer. A non-invasive method for the early detection of disseminating disease would provide an important predictive tool with respect to recurrence and to result in a more appropriate selection of patients for adjuvant therapy. We have used a combination of immunomagnetic separation to isolate epithelial cells from whole blood and detection by nested RT-PCR. Monoclonal antibody BerEP4, which recognizes an epitope expressed by epithelial cells, was covalently linked to magnetic beads. The RT-PCR was performed with oligonucleotides derived from the sequence of the keratin 19 gene. Serial dilutions of SW620 tumor cells were performed in normal blood. We were able to detect 1 colorectal carcinoma cell in 1 ml of whole blood. The clinical applicability of this technique was documented by evaluating patients with a colorectal carcinoma. Two patients presenting a tumor no deeper than the submucosa (stage A) were tested. None of them bad epithelial cells in their blood. For 2 out of the 8 patients who had no detected node involvement (stage B) we were able to early identify a disseminating disease. These patients may thus be at high risk of relapse. Eight patients with histologic evidence of locoregional lymph node involvement were analyzed. Six of them had detectable epithelial tumor cells in their blood. This shows that, in addition to lymph node metastases, the majority of these patients have potential distant metastases in their blood. Finally, we have analyzed 5 stage D patients. Four of them had circulating epithelial tumor cells in their blood.