Radiation exposure to comforters and carers during paediatric molecular radiotherapy.

BACKGROUND: To show whether the incidental radiation exposure received by comforters and carers of children undergoing molecular radiotherapy was kept as low as reasonably achievable and was within English national dose constraints. PROCEDURE: The radiation exposure of adult comforters and carers was routinely monitored with a whole body personal dose meter while the child was in hospital. Data were collected on iodine-131 meta-iodobenzylguanidine (131 I-mIBG), lutetium-177 DOTATATE (177 Lu-DOTATATE), and iodine-131 sodium iodide (131 I-NaI) treatments. RESULTS: Data were available for 50 treatments with high-administered activity double-infusion 131 I-mIBG and 12 single administrations; 15 177 Lu-DOTATATE treatments and 28 131 I-NaI administrations. The median age was 7 years (1-18). The median administered activity of: 131 I-mIBG was 16.2 GBq (6.8-59 GBq) for double infusion patients and 8.1 GBq (5.26-16.25 GBq) for single administrations; 177 Lu-DOTATATE was 7.2 GBq (2.5-7.5 GBq); and 131 I-NaI was 3 GBq for thyroid remnant ablation and 5.5 GBq for cancer therapy. The median number of comforters and carers for all administrations was 2 (range 1-9). The median exposure values for comforters and carers for high-administered activity 131 I-mIBG administrations was 302 µSv (0-5282 µSv); for single fraction 131 I-mIBG 163 µSv (3-3104 µSv); 177 Lu-DOTATATE 6 µSv (1-79 µSv); and 131 I-NaI 37 µSv (0-274 µSv). Only one of the comforters and carers exceeded the dose constraint of 5 mSv. CONCLUSIONS: Doses to comforters and carers were in all but one case within the dose constraint nationally recommended by the Health Protection Agency, now part of Public Health England. New evidence is presented which show that comforter and carer radiation exposure levels from paediatric molecular radiotherapy in routine clinical practice are acceptably low. Pediatr Blood Cancer 2015;62:235-239. © 2014 Wiley Periodicals, Inc.

Paediatric Molecular Radiotherapy: Challenges and Opportunities.

The common contemporary indications for paediatric molecular radiotherapy (pMRT) are differentiated thyroid cancer and neuroblastoma. It may also have value in neuroendocrine cancers, and it is being investigated in clinical trials for other diseases. pMRT is the prototypical biomarker-driven, precision therapy, with a unique mode of delivery and mechanism of action. It is safe and well tolerated, compared with other treatments. However, its full potential has not yet been achieved, and its wider use faces a number of challenges and obstacles. Paradoxically, the success of radioactive iodine as a curative treatment for metastatic thyroid cancer has led to a 'one size fits all' approach and limited academic enquiry into optimisation of the conventional treatment regimen, until very recently. Second, the specialised requirements for the delivery of pMRT are available in only a very limited number of centres. This limited capacity and geographical coverage results in reduced accessibility. With few enthusiastic advocates for this treatment modality, investment in research to improve treatments and broaden indications from both industry and national and charitable research funders has historically been suboptimal. Nonetheless, there is now an increasing interest in the opportunities offered by pMRT. Increased research funding has been allocated, and technical developments that will permit innovative approaches in pMRT are available for exploration. A new portfolio of clinical trials is being assembled. These studies should help to move at least some paediatric treatments from simply palliative use into potentially curative protocols. Therapeutic strategies require modification and optimisation to achieve this. The delivery should be personalised and tailored appropriately, with a comprehensive evaluation of tumour and organ-at-risk dosimetry, in alignment with the external beam model of radiotherapy. This article gives an overview of the current status of pMRT, indicating the barriers to progress and identifying ways in which these may be overcome.