RADIOIMMUNOGUIDED SURGERY BENEFITS FOR RECURRENT COLORECTAL-CANCER

Background: Despite new adjuvant therapy, 50% of patients with colon c ancer will have recurrent disease. This study investigated the use of a radiolabeled monoclonal antibody in locating occult tumor during sur gery for recurrent colorectal cancer. Methods: Twenty-two patients wit h recurrent colorectal cancer underwent surgery using the radioimmunog uided surgery (RIGS) system. All patients were subjected to abdominal and chest computed tomography (CT). Before surgery, patients were inje cted with the CC49 monoclonal antibody (MoAb), anti-TAG antibody label ed with I-125. Ten patients with elevated carcinoembryonic antigen (CE A) levels and no CT findings had a scintigraphy scan with an anti-CEA MoAb labeled with Tc-99. Human antimouse antibody levels of these pati ents were within normal limits. Surgical exploration including liver u ltrasound examination was followed by survey with a gamma-detecting pr obe (GDP). Results: There was MoAb tumor localization in 100% of the p atients. CT found nine tumor sites, traditional surgical exploration 3 0, and the GDP 51, with 44 confirmed by pathology (hematoxylin and eos in). The RIGS system found occult tumor in 10 patients (45.4%) and res ulted in major changes in surgical procedure in 11 patients. In the 10 patients who had scintigraphy scans, 10 tumor sites were identified, whereas RIGS found an additional eight sites. Conclusion: RIGS technol ogy offers a substantial benefit for patients undergoing surgery for r ecurrent colorectal cancer and a better chance of Ending recurrent tum or intraoperatively in patients who have elevated CEA levels with no o ther CT findings.