Probe-guided surgery for colorectal cancer

Anti-CEA-scintigraphy turned out very reliable in detecting primary and recurrent colorectal cancer, its overall accuracy being more than 90 p.c. The intraoperative application of this technology should provide similar results when focussing at extrahepatic tumor deposits, for example in lymph nodes, thus allowing accurate staging of the underlying disease. To test this hypothesis we lauched the following feasibility-study the results of which are compared to those reported in the recent literature. We investigated 20 patients -six with rectum-,14 with colon cancer. 24 hours before surgery they were intravenously given 1 mi of an fab-fragment-antibody to CEA, labeled with 25mCi of 99mTc (CEA-Scan(R)) During surgery the radioactivity in lymphglands regionary for the tumors was measured and compared to the -much lower-activity in healthy nodes. For this we used a scintillation-probe (C-Trak(R)). All lymphnodes of interest were then excised and submitted to frozen section pathology. In 7/20 cases scintimetry led to an up-staging of the disease. In addition we found metastatic spread to lymphnodes that were basically not regionary for the primary tumor. Our results are confirmed by those of other investigators. Scintimetry can precisely identify even very small tumor deposits. So it leads to accurate staging when surgery is still ongoing. In a next step the concept of sentinel-node-diagnosis, which is right now being clinically evaluated, may be applied in colorectal surgical oncology.