HIGH-DOSE 131I-MIBG THERAPIES IN CHILDREN: FEASIBILITY, PATIENT DOSIMETRYAND RADIATION EXPOSURE TO WORKERS AND FAMILY CAREGIVERS

The objective of the present multicentric phase II study (MIITOP) was to determine the response rate, survival and toxicity of tandem infusions of I-131-meta-iodobenzylguanidine (mIBG) and topotecan in children with relapsed/refractory neuroblastoma. High-dose I-131-mIBG therapy programme requires a deal of planning, availability of hospital resources and the commitment of individuals with training and expertise in multiple disciplines. Here in the present study, procedures and the results of patient's dosimetry, as well as family and worker's exposures, were reported for the patients treated in Lille. A total of 15 children were treated with I-131-mIBG between 2009 and 2011 according to the MIITOP protocol. High activity of I-131-mIBG (444 MBq kg21) was administered on Day 0. In vivo dosimetry was used to calculate a second activity, to be given on Day 21, to obtain a total whole body absorbed dose of 4 Gy. Family and worker's exposures were performed too. The injected activity by treatment was from 703 to 11470 MBq. Total whole body absorbed dose by patient ranged from 2.74 to 5.2 Gy. Concerning relatives, whole body exposure ranged from 0.018 to 2.8 mSv. The mean whole body exposure of the radiopharmacist was 4.4 nSv MBq21, and the mean exposure of fingers ranged from 0.18 to 0.24 mSv MBq21 according to each finger. The mean whole body exposure was 33.6 and 20.2 mSv d21 per person, for night nurses and day nurses, respectively. Exposure of doctors was less than 5 mSv d21. Under strict radiation protection precautions, this study shows the feasibility of high-activity I-131-mIBG therapy in France.