Immunoscintigraphy in colorectal cancer: surgeon's perspective

External immunoscintigraphy (IS) is a new imaging tool to diagnose, stage and follow-up solid malignancies. Monoclonal antibodies are raised to tumor-associated antigens, radiolabeled and when injected in the patient localize to the tumor. Detection is with nuclear medicine gamma camera. In colorectal cancer, immunoscintigraphy can be beneficial to the surgeon. With primary colorectal carcinoma, IS detects synchronous primaries, identifies lymph node metastasis, determines extent of disease and detects occult metastasis. Postoperatively, in high-risk patients (Dukes B2, B3 and C lesions) IS assists in the follow-up for recurrence. Particular advantage with IS is seen in pelvic, mesenteric and retroperitoneal recurrences. Rising serum CEA and negative conventional cross-sectional imaging can often be clarified as to site of disease with IS. IS contributes significantly to surgical decision making with alterations in management based on radiolabeled monoclonal antibody scans in 25-32% of primary and recurrent colorectal cancer cases.