Towards homogenization of total body irradiation practices in pediatric patients across SIOPE affiliated centers. A survey by the SIOPE radiation oncology working group

Abstract

Background and purpose: To reduce relapse risk, Total Body Irradiation (TBI) is part of conditioning regimens for hematopoietic stem cell transplantation (HSCT) in pediatric acute leukemia. The study purpose was to evaluate clinical practices regarding TBI, such as fractionation, organ shielding and delivery techniques, among SIOPE affiliated radiotherapy centers. Methods: An electronic survey was sent out to 233 SIOPE affiliated centers, containing 57 questions about clinical practice of TBI. Surveys could be answered anonymously. Results: From over 25 countries, 82 responses were collected. For TBI-performing centers, 40/48 irradiated 10 pediatric patients annually (range: 1-2 to >25). Most indications concerned acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML). Four different fractionation schedules were used, of which 12 Gy in 6 fractions was applied in 91% for ALL and 86% for AML. Dose reduction to the lungs, mostly to a mean dose of 8-10 Gy, was applied by 28/33 centers for ALL and 19/21 centers for AML, in contrast to much less applied dose reduction to the kidneys (7/33 ALL and 7/21 AML), thyroid (2/33 ALL and 2/21 AML), liver (4/33 ALL and 3/21 AML) and lenses (4/33 ALL and 4/21 AML). Conventional TBI techniques were used by 24/29 responding centers, while 5/29 used advanced optimized planning techniques. Conclusion: Across SIOPE, there is a high level of uniformity in fractionation and use of lung shielding. Practices vary regarding other organs-at-risk shielding and implementation of advanced techniques. A SIOPE radiotherapy working group will be established to define international guidelines for pediatric TBI.

Organ sparing total marrow irradiation compared to total body irradiation prior to allogeneic stem cell transplantation

“…Increased toxicity has previously haltered attempted dose escalation, a lower relapse rate with higher radiotherapy dose has not affected the overall survival 5 . A consensus on TBI technique and fractionation 6,7 has been lacking, which hampers comparisons between centres.…”

Total Body Irradiation and Total Skin Irradiation Techniques in Belgium and the Netherlands: Current Clinical Practice

“…describe a European survey and conclude that “there is a high uniformity in fractionation and in lung shielding” and that institutions are increasingly implementing new CT-based techniques. 40 Also, “a radiation therapy working group will be established to define international guidelines for pediatric TBI.” 40 In the Netherlands, all pediatric patients are referred to one dedicated institution ( Fig. 1 ; approximately 25 patients/year).…”

“…Finally, guidelines to practice TBI hopefully will lead to more and more converging treatment techniques. 39 , 40 , 50…”

“…However, this also depends on the expected clinical relevance. Finally, guidelines to practice TBI hopefully lead to more and more converging treatment techniques (e.g., Wong et al, 2018, Hoeben et al, 2021 J o u r n a l P r e -p r o o f…”

Sarcopenia and dosimetric parameters in relation to treatment-related leukopenia and survival in anal cancer

“…All studies have been hampered by small sample sizes and high correlations between the dosimetric parameters, making proper statistical analysis hard to carry out and difficult to interpret. In our opinion, the fact that doses in the range of 12–18 Gy are effective for total marrow myeloablation in the treatment of leukemias is favoring the opinion that lower doses are important predictors for hematologic toxicity [ 27 ]. In our study, only 20.5% (median value) of PBM received < 20 Gy, making any dose–response relationships between PBM dosimetric parameters and hematologic toxicity hard to discern.…”