Effect of reduced-intensity conditioning and the risk of late-onset non-infectious pulmonary complications in pediatric patients.

OBJECTIVE: Late-onset non-infectious pulmonary complications (LONIPCs) contribute to higher morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Therefore, we investigated the risk factors of LONIPCs in pediatric patients.

METHOD: Between 2001 and 2011, 74 pediatric patients (range, 7 months to 22.7 years old; median 6.5 years old), including 29 with a primary immunodeficiency, underwent 80 allo-HSCTs at our institution. Sixty-seven patients who survived more than 3 months after allo-HSCT were analyzed retrospectively. The median follow-up period was 1 973 days (range, 126-5 145 days).

RESULTS: Nine patients (13.4%) developed LONIPCs between 90 and 3 578 days after allo-HSCT. A myeloablative conditioning (MAC) regimen and chronic GVHD were determined as significant risk factors of LONIPCs. None of 18 patients who received the reduced-intensity conditioning (RIC) regimen developed LONIPCs, although there was no difference in overall survival between the MAC and RIC regimen. Notably, two immunodeficient patients who received busulfan-based MAC regimen under 2 years old developed LONIPC with no history of chronic GVHD after 5 years and 10 years from SCT, respectively, suggesting the direct toxicity of busulfan.

CONCLUSION: Our study's findings indicate that the RIC regimen reduces the risk of LONIPCs in pediatric patients.