A study was conducted to elucidate the effect of total body irradiation (TBI) parameters and peri- hematopoietic cell transplantation (HCT) factors on late renal dysfunction among pediatric patients with acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML) after allogeneic HCT. The results appeared in the International Journal of Radiation Oncology, Biology, Physics.
This single-institution retrospective study comprised 123 patients aged 22 or younger with acute leukemia (AML, n=38; ALL, n=85 ) who underwent HCT using a TBI-based regimen from 2006 through 2019. The HCT conditioning regimen consisted of cyclophosphamide, with or without fludarabine, followed by TBI, which was limited to a dose rate of <20 cGy/min but ranged from 8.7-19.2 cGy/min depending on Linac availability. Patients were stratified according to high-dose-rate (HDR; >15 cGy/min; 35%) or low-dose-rate (LDR; ≤15 cGy/min; 65%).
The population of interested received a calcineurin inhibitor to prevent graft-versus-host disease (GVHD). Researchers recorded serum creatinine (Cr) levels baseline and trended post-HCT. Late renal dysfunction was defined in this analysis as persistent increase of Cr >1.2 mg/dL, ≥1.25 times the upper limit of age-dependent normal, and onset ≥3 months after HCT.
According to the results, 11% of patients developed late renal dysfunction: 14% in HDR group vs. 10% in LDR group. A comparative analysis between HDR and LDR groups found no difference in age, sex, remission status, HCT comorbidity index (HCT-CI; predictive of late organ dysfunctions, factoring in baseline Cr) or baseline Cr.
The study showed that more patients in HDR group developed acute GVHD (35% vs. 27%, P=0.05). A univariate analysis revealed that incidence of late renal dysfunction was associated with being aged younger than 12 years at HCT (22% vs. 5% aged >12), demonstrating intermediate-high HCT-CI (22% vs. 6% low HCT-CI), and HDR (24% vs. 8% in LDR).
“Patients [younger than] 12 at HCT, intermediate-high HCT-CI, and HDR were associated with late renal dysfunction post-HCT. Since dose rate is the only modifiable factor, adoption of LDR TBI is recommended,” the researchers concluded.