Risk Factors for Subsequent Central Nervous System Tumors in Pediatric Allogeneic Hematopoietic Cell Transplant: A Study from the Center for International Blood and Marrow Transplant Research (CIBMTR)

Risk Factors for Subsequent Central Nervous System Tumors in Pediatric Allogeneic Hematopoietic Cell Transplant: A Study from the Center for International Blood and Marrow Transplant Research (CIBMTR)
This is a case control study examining the cumulative incidence of CNS neoplasms in patients after allogeneic stem cell transplant. This review was conducted by CIBMTR which comprises the largest database of HSCT information.
Using the CIBMTR database the review was conducted from 1976 to 2008 and included survivors at least one year out of transplant. All CNS tumour cases were reviewed and further information was obtained from the treating centre. A case-control comparison was performed where controls were HSCT patients who did not have a diagnosed CNS tumour. Cox regression models were used to analyze the data from the entire cohort and identify risk factors.
59/8720 participants developed CNS tumours, with half being either astrocytoma or glioblastomas. Compared to the general population, those undergoing allogeneic stem cell transplant for a hematologic malignancy had a 33 times higher than expected rate of CNS tumours (95% CI, 22.98 to 45.77; P=0.0001). The cumulative incidence of subsequent CNS tumours was 1.29% (95% CI .87 to 1.87) at 20 years after transplant. The risk factors for developing CNS tumours were: having an unrelated donor transplant, CNS disease before transplant and radiotherapy exposure before conditioning were risk factors for developing a CNS tumour.
This study is limited by its retrospective nature, and depends on the accuracy of submitted data. This is the first report of this kind and so replication would strengthen the findings.
In the large CIBMTR database no CNS tumours were found in patients transplanted for non-hematologic malignancies or who received non-myeloablative or reduced intensity conditioning (total of 4730 patients). Patients transplanted for hematologic malignancies are at an increased risk of developing a CNS tumour compared to the general population. The identified risk factors from this study are pre-transplant radiation exposure and an unrelated donor.