Immunoscintigraphy using 99mTc-labeled anti-CEA monoclonal antibody for patients with colorectal cancer

Immunoscintigraphy by 99mTc labeled mouse CEA antibody, BW 431/26, was done for 14 patients with colorectal cancer. All patients underwent body scan 6 and 24 hours after administration of 99mTc antibody, 30 mCi/1mg. In 13 out of 14 cases (92.9%) with colorectal cancer, the specific accumulation of 99mTc was shown. The count ratio between the lesion and normal tissue indicating the accumulation of labeled antibody was calculated as 2.6 to 12.8. The hepatic metastasis could be demonstrated as cold spots in one case and as hot spots in the other case. No adverse reaction was noticed in any of patients examined. These results indicate that immunoscintigraphy by 99mTc-CEA antibody detects carcinoma of the colon excellently, and is quite useful clinically. With SPECT, it is possible to localize the site of the lesion more distinctly and to predict the accumulation of the antibody in the tumor as a treatment application.