IMMUNOSCINTIGRAPHY IN PRIMARY COLORECTAL-CANCER

Immunoscintigraphy is an experimental diagnostic nuclear medicine imag ing technique that targets tumor sites with radiolabeled antibodies re active with tumor-associated antigens. Primary tumors, regional lymph node metastases, and distant metastases have been imaged in patients w ith colorectal cancer, and United States Food and Drug Administration (FDA) approval of a commercial preparation of radiolabeled murine mono clonal antibodies for diagnostic use in such patients is expected soon . Immunoscintigraphy is complementary to computed tomography (CT) scan ning in the evaluation of the abdomen and pelvis in patients with colo rectal cancer, and it has the additional capability of serial whole bo dy imaging for detection of distant metastases. However, the clinical utility of immunoscintigraphy is being investigated, and its precise d iagnostic role in patients with primary colorectal cancer has not been adequately defined. The management of selected patients at increased risk of regional or distant spread of tumor likely would benefit from detection of occult disease and a change in clinical staging, but the routine use of immunoscintigraphy in the preoperative evaluation of pa tients with primary colorectal cancer is more problematic. More studie s are required to determine whether it should be used to stage all pat ients before operation or merely be reserved for selected patients at increased risk for metastatic disease.