Hematopoietic Stem Cell/Bone Marrow Transplant in Pediatric Acute Lymphoblastic Leukemia: A Retrospective Analysis of Survival Rate and Treatment-related Mortality

Purpose: Acute Lymphoblastic Leukemia (ALL) makes up nearly 75% of childhood leukemias, making it the most common pediatric malignancy. In cases where refractory disease occurs, allogeneic hematopoietic stem cell transplantation is the therapy recommended. Due to limited information on long-term clinical outcome of transplant recipients in each remission status, the results of this study may help identify a possible timely approach for myeloablative transplant for high risk ALL patients. Additionally, this report describes the difference in survival rates for T cell and B cell ALL populations. Methods: Researchers conducted a comprehensive retrospective chart review of patients identified from the Cook Children's Medical Center (CCMC) Cancer Registry. The population consists of patients diagnosed with ALL at CCMC from January 1, 1986 to December 31, 2012, who underwent a Stem Cell/Bone Marrow transplant. Statistical analysis of the data was performed to determine the survival rates and what factors may have statistically been associated with survival or with death due to the disease or treatment complications, as well as specifically comparing B and T cell ALL survival rates. Results: Overall, CCMC ALL patients who received a bone marrow transplant were found to have a five-year survival rate of 61.3% ± 3.6%, and a ten-year survival was 48.4 % ± 3.9 %. Evaluating the B cell ALL patients separately, the five and ten-year survival rates were 66.7% ± 3.8% and 52.6% ± 4.2%, respectively. The T cell patients when evaluated separately revealed five and ten-year survival rates of 29.5% ± 9.0% and 23.6% ± 8.9%, respectively. Conclusion: The survival rates for CCMC ALL patients who received bone marrow transplants were determined in this study. The data, when looked at separately, showed that there is a statistically significant difference between B cell and T cell survival rates as was hypothesized. T cell ALL survival rates were statistically significantly less than those of B cell ALL cases undergoing transplant. This information is important in helping us to better address the current treatment recommendations for ALL patients and objectively evaluate the effectiveness of those recommendations. The data collected has also provided the opportunity to further evaluate other related factors, such as Philadelphia chromosome and changes in mortality rates over time, and the effect they may have on long-term survival of ALL patients.