Radioimmunoguided Surgery for Colorectal Cancer - An Overview

Many different monoclonal antibodies used experimentally andclinically are highly tumour-specific. Radiolahelling of these antibodies has beensuccessfully accomplished. lmmunoscintigraphy of primary and metastatic cancershas a reported sensitivity of 59 to 70%. However, in many studies, operativeand histologic confirmation is lacking. Radioimmunoguided surgery is a promisingnew adjunctive technique for the surgical treatment of colorectal cancer. Itsreported sensitivity ranges between 70 and 100% and specificity between 66 and100%. In approximately one-third of patients wirh colorectal cancer, additionalintraoperative information concerning the presence of subclinical tumours wasgained using radioimmunoguided surgery. This system has the potential to assistthe surgeon in performing complete resection of cancer and decrease the localrecurrence rate. This could be of particular clinical importance for rectosigmoidtumours where the reported local recurrence rate is as high as 30%. Despite theadvances made, many problems still need to be resolved. The important onesinclude: finding an antibody with high tumour specificity and at the same timerapid clearance from the blood pool and normal tissue - this would avoid thedelay between monoclonal antibody injection and surgery and would make thisapproach more easily accepted by the patient; and use of alternative isotopes forradiolabelling. Radioimmunoguided surgery has the potential to change the waysurgery for colorectal cancer is being performed. It offers the possibility ofimprovement in patient survival