Immunoscintigraphy with iodine-131-labelled monoclonal antibody AUA1 in patients with transitional cell carcinoma of the bladder.

The monoclonal antibody AUA1, labelled with 2 or 3 mCi iodine-131, was administered intravesically to 11 patients with known or suspected bladder carcinoma and was kept in the bladder for 1 h. All patients underwent immunoscintigraphy of the bladder at 2 h and three patients also at 20 h after instillation. Conventional histological and immunohistochemical examinations were performed on tissue samples from tumour and normal areas taken during cystoscopy, carried out 24-h after the instillation. Transitional cell carcinoma of the bladder was present in nine patients whereas dysplastic and normal urothelium was found in the remaining two patients, respectively. Six out of nine tumours were successfully imaged at the 2-h scan. Normal urothelium showed no uptake while dysplastic urothelium was positive on imaging. Successful detection was correlated with size and grade of tumour in almost all cases. Tumors with a diameter of 1 cm or less were not detected. Four out of five grade II tumours and two out of three grade III tumours were detected with this method. The method is a promising one although further studies using more suitable isotopes and/or monoclonal antibodies are required to increase its sensitivity.