The optimal therapy for childhood MDS has not been established. A key issue in thinking about therapy for pediatric patients with MDS is that these disorders usually involve a primitive hematopoietic stem cell. Thus, allogeneic hematopoietic stem cell transplantation (HSCT) is considered to be the optimal approach to treatment for pediatric patients with advanced MDS. Unresolved issues include determining the best transplant preparative regimen and source of donor cells.[25,26] However, some data are important to consider when making decisions. For example, disease-free survival has been estimated to be between 50% to 70% for pediatric patients with advanced MDS using myeloablative transplant preparative regimens.[27,28,29,30,31] While using nonmyeloablative preparative transplant regimens are being tested in patients with MDS and AML, such regimens are still investigational for children with these disorders, but may be reasonable in the setting of a clinical trial or when a patient's organ function is compromised in such a way that they would not tolerate a myeloablative regimen.[32,33,34]
The question of whether chemotherapy should be used in high-risk MDS has been examined. The Children's Cancer Group 2891 trial accrued patients between 1989 and 1995, including children with MDS. There were 77 patients with refractory anemia (n = 2), refractory anemia with excess blasts (n = 33), refractory anemia with excess blasts in transformation (n = 26), or AML with antecedent MDS (n = 16) who were enrolled and randomly assigned to standard or intensively timed induction. Subsequently, patients were allocated to allogeneic HSCT if there was a suitable family donor, or randomly assigned to autologous HSCT or chemotherapy. Patients with refractory anemia/refractory anemia with excess blasts had a poor remission rate (45%), and those with refractory anemia with excess blasts in transformation (69%) or AML with history of MDS (81%) had similar remission rates compared with de novo AML (77%). Six-year survival was poor for those with refractory anemia/refractory anemia with excess blasts (28%) and refractory anemia with excess blasts in transformation (30%). Patients with AML and antecedent MDS had a similar outcome to those with de novo AML (50% survival compared with 45%). Allogeneic HSCT appeared to improve survival at a marginal level of significance (P = .08). Based on analysis of these data and the literature, the authors concluded that children with a history of MDS who present with AML and many of those with refractory anemia with excess blasts in transformation do as well with AML therapy at diagnosis as children with AML. An exception to this conclusion is children with AML with a precedent MDS and monosomy 7; these patients have a very poor prognosis and are usually treated with some type of allogeneic HSCT. An analysis of 37 children with MDS treated on Berlin-Frankfurt-Munster AML protocols 83, 87, and 93 confirmed the induction response of 74% for patients with refractory anemia with excess blasts in transformation and suggested that transplantation was beneficial. Another study by the same group showed that with current approaches to HSCT, survival occurred in more than 60% of children with advanced MDS, and outcomes for patients receiving unrelated donor cells were similar to those for patients who received matched-family donor (MFD) cells.