Radioimmunoguided surgery for recurrent colorectal cancer manifested by isolated CEA elevation

BACKGROUND. Carcinoembryonic antigen (CEA) is a sensitive marker for detect ing recurrent colorectal carcinoma. An asymptomatic rise of CEA can precede by several months the detection of recurrent cancer by standard imaging mo dalities. Yet, surgeons are hesitant to operate solely on the basis of an o bserved increase in CEA. We investigated the ability of radioimmunoguided s urgery to enhance the surgeon's capability of detecting intraabdominal dise ase in these patients. METHODS. Nineteen patients who underwent radioimmunoguided surgery for susp ected tumor recurrence based solely on elevated CEA were included in the st udy. They underwent colonoscopy and CT of the abdomen and chest, all of whi ch were negative. They then underwent scintigraphy scan with an anti-CEA mo noclonal antibody (MoAb) labeled with Tc-99m or Indium I-111. All patients were injected with the CC49 MoAb (an anti-TAG-72 tumor-associated glycoprot ein) labeled with I-125 three weeks before surgery. During surgery, traditi onal exploration was followed by survey with a gamma-detecting probe. RESULTS. Traditional surgical exploration identified 26 recurrent tumors: 7 hepatic, 8 pelvic, 6 retroperitoneal, 3 colonic, 1 splenic, and 1 anastomo tic. Radioimmunoguided surgical exploration confirmed all recurrent tumors and identified additional tumor sites in seven patients that resulted in ch anging the surgical plan. CEA scans correlated with intraabdominal findings in seven patients. Abdominal pathology did not correlate completely with t he scans in three patients, and CEA scan results were undetermined in two p atients. CONCLUSION. Patients with elevated CEA and no other findings should be oper ated upon without delay, and radioimmunoguided surgery should be used to en hance the surgeon's knowledge of the extent of disease. Cancer 2000;89:1692 -8. 2000 American Cancer Society.