Radioimmunoguided surgery for colorectal cancer

Background Improving the survival rate of surgical treatments of cancer depends upon accurate staging of disease and the subsequent ability to completely resect the lesions. Radioimmunoguided surgery (RIGS) has been employed in the treatment of colon and rectal cancer, and a multicenter trial is under way. Methods Twenty-eight patients with either primary or recurrent colorectal cancer were injected with the monoclonal antibody CC49 labeled with iodine 125. A hand-held gamma-detecting probe was used intraoperatively to detect radiolabeled antibody. At surgery the patients underwent both traditional and RIGS explorations. Results RIGS detected radiolabeled antibody in 73% (14 of 19) of patients with primary colorectal cancer and in 100% (7 of 7) of patients with recurrent disease. Based on RIGS, 26% (5 of 19) of patients with primary cancer were upstaged from stage I/II to stage III/IV. Conclusions Although the final results of this phase III trial are incomplete, RIGS appears to provide immediate, valuable information that is not available from more conventional methods.