Cumulative incidence of developing thyroid dysfunction after HCT in childhood. (A) Cumulative incidence of developing thyroid dysfunction after hematopoietic cell transplantation divided by type of preparative regimen received: TBI, busulfan, busulfan + TBI, or cyclophosphamide only. (B) Cumulative incidence of developing thyroid dysfunction after hematopoietic cell transplantation divided by patient age. The bottom curve represents patients who received transplants between 10 and 17 years of age and the top curve represents patients who received transplants between 0 and 9 years of age.