Prior to hematopoietic stem cell transplant (HSCT), patients with non-Hodgkin lymphoma (NHL) typically undergo total body irradiation and chemotherapy as part of a conditioning regimen. In order to reduce the risk of relapse following HSCT, some patients with higher risk disease may receive higher doses of radiation. However, according to a study presented recently at Transplantation and Cellular Therapy 2020, higher doses of radiation may be associated with shortened survival in patients with NHL. The study evaluated outcomes in 413 patients with NHL who received a reduced-intensity conditioning regimen of fludarabine plus 2 Gy or 4 Gy radiation prior to HSCT.
Patients receiving higher radiation doses were more likely to die from causes other than relapse and had a shorter survival compared to those receiving lower radiation doses. The 5-year nonrelapse mortality rate was 47% in the higher dose cohort, compared to 28% in the lower dose cohort (P = .005). Five-year overall survival (OS) rates were 31% with the higher radiation dose and 51% with the lower dose (P = .001). Similar benefits were seen for the lower radiation dose in risk for relapse/progression and progression-free survival. The 100 day graft failure rate was slightly higher in the cohort receiving the higher radiation dose, but this difference was not statistically significant.
The investigators concluded that a radiation dose of 2 Gy is more effective at prolonging survival in patients with NHL undergoing HSCT, primarily due to higher rates of nonrelapse mortality in patients receiving higher radiation doses.
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