A clinical comparison of the tumour-imaging radiopharmaceuticals 67Gallium-citrate and 111Indium-labelled bleomycin.

Two tumour-imaging agents, 67Gallium-citrate and 111Indium-bleomycin have been assessed in a clinical trial. Both the quality of tumour image and correlation with known sites of disease has been compared by scanning with the two agents in a variety of malignant diseases. In addition, comparative uptakes of the agents have been measured in biopsy samples. In 28 scanning examinations using the agents sequentially, 67Gallium-citrate provided a more satisfactory tumour image and had closer clinical correlation with known sites of disease in 14 cases. Scans were felt to be of similar quality in 14 cases. There were no examples where 111Indium-bleomycin scans were found to be superior to 67Gallium-citrate. A number of biopsy samples of spleen, liver and lymph nodes were obtained from patients undergoing staging laparotomies for lymphomas in whom small doses of 67Gallium-citrate and 111Indium-bleomycin had been injected shortly before operation. Seven of the spleen samples were infiltrated with tumour and five of these contained less 67Ga than 111In; in contrast four of the five tumour-infiltrated lymph nodes showed 67Ga concentrations greater than those of 111In. It is concluded that 67Gallium-citrate is a more useful tumour-imaging agent than 111Indium-bleomycin, at least for lesions situated above the diaphragm. The value of 111Indium-bleomycin in the demonstration of abdominal malignancies has not been fully assessed in this study. Trials of new tumour imaging agents should as far as possible be compared directly with the best available alternative agent in a controlled study.