Radioimmunoguided surgery (RIGS) in recurrent colorectal cancer

Since 1986, 191 patients with recurrent colorectal cancer have undergone surgical exploration 2 to 43 days after injection of 1.0 to 0.25 mg of monoclonal antibody (MAb) (B72.3 or 17-1A) radiolabeled with 5.0 to 1.0 mCi of 125I. The intraoperative use of a hand-held gamma detector (Neoprobe 1000) demonstrated that MAb identified tumor in 73% of cases. Clearer intraoperative definition of tumor margins and identification of occult tumor assisted the surgeon in the resection of liver metastases as well as nodal and pelvic disease. Unsuspected nodal disease was identified. The external use of the Neoprobe to scan the sacral region and intrarectal and intravaginal use led to the avoidance of operative procedures by defining inoperable disease. In approximately 25% of cases, the surgical procedure was modified based on Neoprobe findings. RIGS system provides a method of immediate intraoperative staging which may prevent additional recurrences, lead to earlier institution of adjuvant therapy, and result in improved survival.