Radio-immunotargeting in colorectal carcinoma

Colorectal cancer is one of the most frequently studied diseases for investigating cancer detection using radiolabelled monoclonal antibodies. From many clinical studies it has become clear that with radio-immunotargeting (RIT) it is possible to visualise approximately 70% of known sites of colorectal cancer and to find otherwise occult tumour deposits in approximately 10% of patients. The intra-operative use of a gamma detection probe increases the detection rate of clinical occult intra-abdominal tumour sites to 30-40%. However, this clinical experience has also disclosed the many difficulties and pitfalls connected with this technique, with respect to antibody-, tumour-, patient- and isotope-related factors. Upstaging or early disclosure of disseminated disease by RIT has not proven to be beneficial in terms of improved survival, but might be of use in the management of an individual patient. The laborious and costly RIT technique, difficult scan interpretation and the lack of proven survival benefit precludes its routine use in clinical practice. However, the promising results warrant further study to improve the technique, and to validate the clinical usefulness of radio-immunotargeting.