Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with ¹³¹I‐metaiodobenzylguanidine with implications for the activity to administer

Abstract

Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with (131)I-metaiodobenzylguanidine with implications for the activity to administer.MINGUEZ GABINA, PABLO; Flux, Glenn; Genolla, Jose; Guayambuco, Sonia; Delgado, Alejandro; Fombellida, Jose Cruz; Sjögreen Gleisner, Katarina , Flux, G., Genolla, J., Guayambuco, S., Delgado, A., Fombellida, J. C., & Sjögreen Gleisner, K. (2015). Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with (131)I-metaiodobenzylguanidine with implications for the activity to administer. Medical Physics, 42(7), 3969-3978. DOI: 10.1118/1.4921807General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Methods: Nine NB patients and six NET patients were included, giving in total 19 treatments as four patients were treated twice. Whole-body absorbed doses were determined from doserate measurements and planar gamma-camera imaging. For six NB and five NET treatments, red-marrow absorbed doses were also determined using the blood-based method.Results: Dosimetric data from repeated administrations in the same patient were consistent. 30In groups of NB and NET patients, similar whole-body residence times were obtained, implying that whole-body absorbed dose per unit of administered activity could be reasonably well described as a power function of the patient mass. For NB, this functional form was found to be consistent with dosimetric data from previously published studies. The whole-2 body to red-marrow absorbed dose ratio was similar among patients, with values of 1.4±0.6 to 35 1.7±0.7 (1 standard deviation) in NB treatments, and between 1.5±0.6 and 1.7±0.7 (1 standard deviation) in NET treatments. Conclusions:The consistency of dosimetric results between administrations for the same patient supports prescription of the activity based on dosimetry performed in pre-treatment studies, or during the first administration in a fractionated schedule. The expressions obtained 40 for whole-body absorbed doses per unit of administered activity as a function of patient mass for NB and NET treatments are believed to be a useful tool to estimate the activity to administer at the stage when the individual patient biokinetics has not yet been measured.

Impact of Whole-Body Radiation Dose on Response and Toxicity in Patients With Neuroblastoma After Therapy With131I-Metaiodobenzylguanidine (MIBG)

“…Furthermore, we found trends to suggest correlations between both MYCN amplification and relative Curie score. In contrast to our hypothesis and results of previous studies, we did not find a significant correlation between WBD and response or toxicity …”

“…To account for this, we conducted a subanalysis of MIBG monotherapy protocols and again no significant association was observed. A recent study also found no correlation between grade of hematologic toxicity and WBD, but they suggested that the lack of correlation might be attributed to small sample size, wide age variance, or prior hematotoxic treatments . One possible explanation for the low correlation in our study is the narrow range of WBD.…”

“…Our findings regarding the correlation between WBD and 131 I‐MIBG activity support the results of previous studies . The strong positive correlation of WBD to 131 I‐MIBG activity per kilogram suggests that activity prescriptions for 131 I‐MIBG therapies should be made based on patient weight as opposed to a predetermined total activity dose in order to achieve a targeted WBD.…”

“…A recent study by Minguez et al. proposed an equation, which describes whole‐body absorbed dose per unit of administered activity as a function of patient mass, as an alternative for prescriptions of activity on first administration when dosimetry data for the individual patient are unknown …”

Biologically effective dose in fractionated molecular radiotherapy—application to treatment of neuroblastoma with131I-mIBG

“…The patient mass was 63 kg, which according to the protocol by Gaze et al (2005) implied an administered activity of 28 GBq for the first administration, and assuming that the whole-body absorbed dose would be close to 2 Gy (Minguez et al, 2015), another 28 GBq for the second administration. However, since the maximum authorised 131 I activity at the Gurutzeta-Cruces University Hospital is 14.8 GBq, a modification of the schedule was necessary.…”