Single-Fraction Total Body Irradiation for Non-Myeloablative Treatment of Sickle Cell Disease
Abstract
Purpose
Total body irradiation (TBI) is a well-established conditioning regimen prior to hematopoietic stem cell transplant (HSCT) for treatment of leukemia cancers. This study reports on a Central-Asian national referral cancer centre’s experience in treating one of the largest global patient cohorts to receive TBI as part of HSCT for benign sickle cell disease (SCD) non-myeloablative treatment.
Methods
Following IRB approval, records of SCD patients who received TBI were retrospectively reviewed (2015-2024). Data extraction included patient demographics, disease information, TBI treatment parameters, radiation-induced toxicities and in-vivo measurement results to verify dose uniformity at four locations on each patients’ body.
Results
275 patients were treated, age=24.6 ± 8.5 years old, mostly male (54.9%). 95.6% survived after 5-years, 4.7% reported graft failure, and 92% had ECOG status=0 at last contact. 89.5% of donors were relatives. The total simulation and treatment planning time were < 1 hour. TBI delivery used simple extended-SSD on an Elekta linac with 10 MV bilateral beam placement and rice bags for beam uniformity. 13.0% and 85.9% of patients received single-fraction 200 cGy or 300 cGy, respectively, to the patient’s midline (maximum separation= 18–44 cm). Maximum monitor unit delivery was 10532, and 96.7% of male patients had testicular shielding. No lung shielding was needed. Acute radiation-related toxicities were reported for 53.1% of patients (grade3=8%). In-vivo OSLD measurements read <10% dose uniformity.
Conclusion
SCD is recognized as a common genetic disorder in certain populations, with serious adverse effects. As we witness a 20-year 14% global increase in SCD rates, single-fraction TBI is shown to play an important role in its treatment. This retrospective study reported technical and clinical outcome data related to TBI for SCD treatment of a large patient cohort, and highlighted the role of a low-resource, yet effective and practical TBI technique in treatment of SCD patients.