Objective: Radioimmunoguided surgery (RIGS) is the method that during the operation details the results of preoperative immunoscintigraphy. The aim of study is to find the most acceptable method of assessing the RIGS results during the operation of colorectal cancer patients in order to obtain the highest sensitivity of the method. Methods: 47 patients with colorectal carcinoma were operated on. Two kinds of radiopharmaceuticals were used in the study. Monoclonal antibody against tumor antigen TAG 72 labelled with 111 In (Onco-Scint) and the Fab´fragmented monoclonal antibody against tumor antigen CEA labelled with 99m Tc (CEA-Scan). In the first 38 patients the histological results were compared with the intraoperative RIGS results. The new established method was then used in operations of the following patients of the investigated group. Results: Four different parameters of intraoperative measurement were evaluated in relation to histological results. The nearest to the morphological reality was the method, where the following ratios of radioactivity values were taken as guide: Lymphonode / Healthy tissue of mesocolon: Tumor / Healthy part of colon. The evaluation of the group of the 47 patients exhibited increased sensitivity of this parameter. Conclusions: The new method of intraoperative radioimmunodetection assessment, up to now still not published in the literature enabled to achieve the acceptably high sensitivity of followed diagnostical method using Oncoscint and CEA-Scan. The results published in this paper represent the preliminary information concerning the study of the more extensive set of patients.

        Key words: colorectal cancer – intraoperative radioimmunodetection