|Budget Amount *help
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Imaging using radiolabeled monoclonal antibody (MAb) to tumor-associated antigen is potentially specific approach to qualitative diagnosis. The MAbCEA102 against CEA was produced by immunization with purified CEA,and used as a radiotracer for the imaging of colorectal cancer. To investgate the specific accumulation of radiolabeled CEA102, autoradiographic study using Fuji Computed Radiography (FCR) was performed, and predominant localizations of 131-I-labeled-CEA102 were observed in primary tumors and even small liver metastases. We then applied 131-I-labeled-CEA102 to 20 cases with liver metastases, local recurrences, and/or primary tumors. Overall sensitivity was 71.4%, and no false positive was observed. Since 131-I has energic gamma-ray emission, and high accumulation of free 131-I in bladder, we attempted using 111-In as a radiotracer which has a short half life and provides to use Single Photon Emission CT (SPECT) . We applied to 10 cases (primary tumor 1, CEA producing tumor of ileum 1, and local recurrence of rectal cancer 8) using 111-In-labeled CEA102. Overall sensitivity was 70%. Although this radiotracer was not suitable to detect liver metastasis due to high accumulation of 111-In in liver, it was especially useful to diagnose local recurrence of rectal cancer using Emission CT.The above results demonstrated that radioimaging has a great potential in qualitative diagnosis.