PO-06. Innovation approaches to total body irradiation with simultaneous dose escalation to bone marrow in children with oncohematological diseases
Daria A. Kobyzeva, Anna A. Loginova, Larisa N. Shelikhova, Francheska Ya. Kanestri, Rimma D. Khismatullina, Maria A. Ilyushina, Michael A. Maschan, Aleksey V. Nechesnuyk
Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
Contact: Dr. Daria A. Kobyzeva, phone: +7 (916) 595-86-35, e-mail: daria.kobyzeva@gmail.com
Summary
Purpose of our work was to develop and compare the conformal the intensity-modulated total body irradiation (IMRT) with simultaneous boost to bone marrow (TBI + boost to BM) and targeted bone marrow and lymphoid system irradiation (TMLI) for pediatric patients with acute leukemia.
Materials and methods
This work describes 32 patients who underwent TBI + boost to BM and 25 patients received targeted bone marrow and lymphoid system irradiation (TMLI) during conditioning regimen before allogenic stem cell transplantation. All the patients received simultaneous radiation dose escalation to bone marrow up to 15 Gy total dose (Figure 1). The radiation treatment was held with using intensity-modulated conformal irradiation on Hi-Art TomoTherapy (TomoTherapy-based TBI) and Elekta Synergy linear accelerator.
Results
From January 2017 to December 2022, radiation therapy treatment was held on 57 patients. Thirty-five patients had acute myeloid leukemia (ALL), 13 patients had AML, 9 patients had other diseases. Forty-three patients (73%) had active disease at the moment of TBI. The fractionation regimen was applied two times per day during three subsequent treatment days. The additional bone marrow dose escalation did not influence the duration of conditioning period. We did not observe any lethal radiation-induced complications. Three cases (9%) of veno-occlusive disease were observed in the TBI + Boost to BM patients’ group. The comparison of acute toxicities in the both group of irradiated patients (according to RTOG scale) is presented on Table 1.
The follow-up period was from 0 to 54 months (median of 38.0±4.4 months). During this period, we observed 13 recurrences in TBI + Boost to BM group of pts, 12 of them were localized in the marrow areas exposed to escalated doses. Among those patients who received TMLI, we registered 9 relapses from bone marrow, and no recurrencies were observed from the radiation treatment in the areas of reduced radiation dose.
Conclusions
We have developed and introduced two techniques of the optimized conformal total body irradiation with simultaneous dose escalation to the bone marrow. Moreover, we have also compared acute toxicity rate for the both treatment modalities. The presented results shows that the more targeted approaches, such as TMLI, are more appropriate and it may reduce the acute toxicity rates without impacting the results of radiation therapy.
Keywords
Total body irradiation, total marrow irradiation, intensity-modulated radiation therapy, hematopoietic stem cell transplantation.
Figure 1. Variations of total body irradiation methods
Table 1.
