Immunoscintigraphy of primary and metastatic colorectal cancers with radiolabelled monoclonal antibodies anti-CEA.

Thirteen patients with a diagnosis of primary colorectal tumour and 68 patients previously operated for colon cancer underwent an immunoscintigraphy carried out with monoclonal antibodies anti-CEA F(ab')2, labelled with 131I or 111In. These studies led to the detection of all primary tumours and of most of their associated lesions (7/8). In this group 15 neoplastic deposits previously undetected were demonstrated, allowing an improvement in the patient staging before the operation. In the group of the 68 operated patients, immunoscintigraphy succeeded in imaging 96 out of 121 known lesions: the best outcomes were obtained for abdominal and pelvic recurrences as well as for lymph nodes lesions. The lowest levels of sensitivity were observed for liver metastases. An enhancement of the immunoscintigraphy sensitivity was obtained when the radiopharmaceutical was injected intraperitoneally. In 50 patients, this alternative administration route was successful in detecting 91/107 cancer deposits and, in particular, liver metastases were found out in 36/42 cases.