A radiolabelled iodobenzamide for malignant melanoma staging

123I-N-(di-ethylamino-2-ethyl) 4 iodobenzamide (I-BZA) has been put forward by the Clermont-Ferrand INSERM U71 group (France) as a tracer for malignant melanoma. We report on the clinical results obtained in 56 studies performed on 48 patients. Whole body scans along with spot views were obtained after injection of 185 MBq of I-BZA. The scans were read by three independent observers and correlated to the clinical findings and the other imaging modalities available, taking into account all lesions larger than 1 cm. Patients were classified into two groups on the basis of a post-treatment survey of patients: group I, in complete remission (24 scans); group II: documented metastases (32 scans). In group 1, 21 studies were truly negative. However, three studies showed positive results. Only one turned out to be a false positive (specificity 95%), the other two revealed unknown lesions and modified the patients' management. In group II, 73% of the known metastases were detected with higher sensitivities (> 80%) for eye and orbit, lung and abdomen. One false positive was reported and four new lesions were detected. I-BZA scintigraphy has the same sensitivity as immunoscintigraphy with higher specificity and without the risk of xenoimmunization. It is a useful tool for staging malignant melanoma which can improve patient management.