RADIOIMMUNOSCINTIGRAPHY OF RECURRENT COLORECTAL-CARCINOMA USING IN-111 LABELED MURINE MONOCLONAL ANTIBODY-B72.3 - A COMPARISON WITH CONTRAST-ENHANCED COMPUTED-TOMOGRAPHY

Ten patients underwent contrast-enhanced abdominal computed tomographi c (CT) carcinoembryonic antigen (CEA) measurement and murine In-111-B7 2.3 monoclonal antibody radioimmunoscintigraphy for recurrent or resid ual colorectal carcinoma. All patients had undergone primary colorecta l tumour resection at a median of 3 (range 1-18) months previously. Hi stological analysis of pelvic tissue biopsies confirmed that six patie nts had recurrent or residual colorectal cancer and that four were tum our free. Whilst scintigraphy correctly showed all six patients with r ecurrent or residual disease, both CT and CEA measurement were correct in only four patients. In the four patients without recurrent cancer, CT was correct in two patients whilst scintigraphy and CEA measuremen t were accurate in three patients. Six out of the 10 patients showed m arked nonspecific colonic excretion of radiolabelled antibody which wa s correctly interpreted in five patients. Future prospective studies c omparing CT scans, CEA estimation and B72.3 radioimmunoscintigraphy in a larger group of patients with suspected residual or recurrent color ectal adenocarcinoma may help to define the respective sensitivity and specificity of these techniques.