[Immunoscintigraphy or intraoperative isotopic detection of colorectal neoplastic lesions using labelled monoclonal...

20 patients submitted to surgery for colo-rectal malignancies, had I.V. injection of 500 microcuries of 125 I F (ab')2 anti CEA, 3 to 5 days preoperatively, after previous thyroid blockade by iodine. At the time of laparotomy, any obvious neoplastic growth or suspicious area was checked by "intra-operative scintigraphy" according to the technique already developed in thyroid surgery by Sten Lennquist. Result was considered as positive when the uptake ratio suspicious tissue/normal tissue was greater normal tissue than 1.5. 18 out of 19 pathologically proven carcinomas, 1 out of 3 liver metastasis, 3 out of 3 extra-hepatic deposits, and 3 out of 9 metastatic nodes only were positive at scintigraphy. These results are not correlated with preoperative plasma level of CEA. Perhaps some colo-rectal carcinomas might be able to secrete CEA but not to excrete it. Improvement of intraoperative decision-making by this method needs further experience to be appreciated. It was helpful in 2 of our 20 cases.