The clinical value of imaging with antibody to human chorionic gonadotrophin in the detection of residual choriocarcinoma.

Choriocarcinoma can be imaged by external scintigraphy after intravenous administration of radiolabelled antibody directed against human chorionic gonadotrophin (HCG). The purpose of this study was to investigate whether antibody imaging was sufficiently sensitive and specific to improve the selection of patients for surgical resection of localised deposits of drug resistant or recurrent choriocarcinoma. Eighteen patients with raised serum HCG concentrations in whom the site of tumour was not known were investigated by antibody imaging and conventional imaging methods. When the tumour appeared localised, resection was attempted. Tumour was found at all sites in which both antibody imaging and conventional imaging methods were positive. Antibody imaging gave false positive results in 2 of 18 patients and false negatives in 5. Computerised tomography was false positive in one case and false negative in 2. In these patients, antibody imaging gave true negative and true positive results respectively. Of 8 patients with positive antibody imaging in whom resection was attempted, 5 achieved sustained complete response with up to five years follow up. It is concluded that antibody imaging is useful in selection of patients for surgery in drug resistant or recurrent choriocarcinoma.