IN-111-CYT-103 SCANNING IN RECURRENT COLORECTAL-CANCER - DOES IT AFFECT STANDARD MANAGEMENT

PURPOSE: In a blinded fashion, radiolabeled B72.3 was investigated in operative cases of recurrent colorectal cancer to determine if diagnos tic accuracy would be improved to ultimately maximize curability and m inimize interventional morbidities. METHODS: Study patients underwent conventional evaluation including history, physical examination, abdom inal/pelvic computed tomographic scan (CT), colon examination, and car cinoembryronic antigen (CEA) determination, with select magnetic reson ance imaging and ultrasonographic imaging as indicated. Murine monoclo nal antibody B72.3 was labeled with indium-111 (In-111-CYT-103 provide d by Cytogen) and scans obtained at 48 hours and, selectively, at 72 a nd 96 hours. Unlike previous studies, the operating surgeon was blinde d to In-111-CYT-103 abdominal scan results until surgical exploration was complete. RESULTS: Of 15 study patients (10 male; 5 female), avera ge age was 57 years, and average CEA was 10 ng/ml (with eight elevated CEA levels). A single patient did not undergo surgery because of pres ence of pulmonary metastases identified on CT scan but not identified on a In-111-CYT-103 scan. Laparotomies included resection and intraope rative radiation (10), resection alone (1), and biopsy only (3). CT an d In-111-CYT-103 scans were compared with operative findings. CT scans had an accuracy and positive predictive value of 47 and 100 percent, respectively, whereas those of In-111-CYT-103 scan were 60 and 82 perc ent, respectively. Contribution of the scan to diagnosis and managemen t was graded by the surgeon as no effect (67 percent), beneficial effe ct (13 percent), or negative effect (20 percent). CONCLUSIONS: In-111- CYT-103 was more accurate compared with CT scan, but when value of the scan was examined with respect to its potential contribution to patie nt management, it was beneficial in only 13 percent of patients. Furth er refinements may enhance the value of antibody imaging techniques.