Role of 131I-metaiodobenzylguanidine (MIBG) in the treatment of neuroendocrine tumours. Experience of the National Cancer Institute of Milan

45 patients with neuroendocrine tumours (22 neuroblastomas, 10 phaeochromocytoma s, 3 paragangliomas, 6 medullary thyroid carcinomas and 4 carcinoid s) underwent 131I-MIBG therapy. All patients, with the exception of 5 phaeochromocytoma cases with non operable disease, had previously been treated with conventional therapies. Patients had a previous diagnostic scintigraphy with 131I-MIBG (activity 20-44.4 MBq) or with 123I-MIBG (activity 74-222 MBq). All treatments were repeated at not less than 4-weekly intervals. The neuroblastoma patients were divided into two groups: the first included 14 patients with advanced metastatic disease not responding to previous treatments; the second included 8 patients with documented residual neuroblastoma tissue that could not be surgically removed after first-line therapy. In neuroblastoma patients with advanced disease resistant to previous therapies 2 out of 14 showed a partial response, 9 stable disease and 3 progression of cancer. In neuroblastoma patients with residual disease (7 evaluable out of 8) it was obtained 3 partial responses; a stable response was observed in 3 patients. The result of MIBG therapy in the group of phaeochromocytoma patients (9 evaluable out of 10) consisted of 3 partial responses, 5 stable disease and 1 progression. Evaluation of the response carried out on the basis of the biochemical parameters increased the responses and MIBG therapy showed good effectiveness in controlling the functional symptoms. In the group of paraganglioma patients it was observed 1 complete, 1 partial and 1 stable response. In patients with medullary thyroid carcinoma a partial response was observed in 1 patient with mediastinal metastases and 2 disease stabilizations were seen in another 2 patients. On the basis of personal experience it can be concluded that 131I-MIBG therapy is effective and also well tolerated