USE OF CARCINOEMBRYONIC ANTIGEN RADIOIMMUNODETECTION AND COMPUTED-TOMOGRAPHY FOR PREDICTING THE RESECTABILITY OF RECURRENT COLORECTAL-CANCER

Objective The objective was to determine the role of arcitumomab (CEA- Scan; Immunomedics, Morris Plains, NJ), an anticarcinoembryonic antige n (CEA) Fab' labeled with technetium-99m, in the presurgical evaluatio n of patients with recurrent or metastatic colorectal carcinoma. Summa ry Background Data Surgical resection is the only method known to cure recurrent or metastatic colorectal carcinoma. The location and extent of disease must be determined before surgery. The role of antibody im aging, a new cancer detection modality, in preoperative evaluation for resection of locally recurrent or metastatic colorectal cancer has no t been established, either alone or in combination with standard diagn ostic modalities. Methods In a blinded analysis of 209 patients with k nown or suspected colorectal cancer, the accuracy of arcitumomab, alon e and combined with computed tomography (CT), was compared to that of CT for predicting abdominopelvic tumor resectability by correlating th e results with surgical and histopathologic findings. Results Arcitumo mab alone or combined with CT was found to be significantly more accur ate for predicting surgical outcome than CT alone. When the results of CT and arcitumomab were concordant for abdominopelvic resectability, nonresectability, or absence of disease, the prediction was accurate i n 67%, 100%, and 64%, respectively. Thus, the concordance for nonresec tability (100% correct) may obviate the need for other diagnostic moda lities or exploratory surgery. When the two tests were discordant, arc itumomab was correct substantially more often than CT. Because the liv er is the most common site of distant metastasis in colorectal cancer, a subset of patients with hepatic disease was also analyzed; findings were similar to the overall resectability results. The product's safe ty profile was excellent: the incidence of induction of an immune resp onse against arcitumomab was <1% and that of potentially adverse event s was 1.2%. Conclusions The accuracy of arcitumomab for assessing rese ctability status is greater than that of CT, both in all patients unde rgoing evaluation for curative abdominopelvic resection of colorectal cancer and in the subset of patients with suspected or proven liver me tastases. The additional use of arcitumomab with CT potentially double s the number of patients who could be saved the cost, morbidity, and m ortality of unnecessary abdominopelvic surgery and increases those who are potentially resectable for cure by 40%.