Day +100 Platelet Count Predicts Survival After Allogeneic Hematopoietic Stem-Cell Transplantation in Children With Hematologic Malignancies.

INTRODUCTION:Recovery of platelet count by day 100 after hematopoietic stem-cell transplantation (HSCT) is affected by many factors and has been reported to be a predictor of overall survival (OS) in a variety of diseases and donor types. We investigated the correlation between day +100 platelet count and OS after allogeneic HSCT in a relatively homogeneous cohort of pediatric patients with hematologic malignancies. PATIENTS AND METHODS:We conducted a retrospective study of 152 consecutive patients who underwent allogeneic HSCT at the Children's Cancer Hospital Egypt between 2009 and 2015 with a minimum follow-up duration of 1 year after transplantation. All eligible patients received myeloablative conditioning, and all had matched related donors. Patients who survived without relapse until day 100 after HSCT were divided into 2 groups: early platelet recovery (EPR; platelet count ≥ 100 × 109/L at day +100 after transplantation) and delayed platelet recovery (DPR; platelet count < 100 × 109/L at day +100 after transplantation). RESULTS:At day +100, 113 patients (74%) had EPR and 39 patients (26%) had DPR. With a median follow-up of 41 months (range, 12-93 months), 41 patients (27.2%) died, 35 of relapsed disease. The 3-year disease-free survival (DFS) and OS were 68 ± 7.84% and 71.9 ± 7.84%, respectively. The 3-year OS was 77.9% in the EPR group and 57.1% in the DPR group (P = .006). Three-year DFS of the EPR and DPR groups were 73.2 ± 9% and 54.8 ± 16.3%, respectively (P = .02). Incidence of disease relapse for EPR and DPR patients was 22.6% and 39.5%, respectively (P = .04). Multivariate analysis for survival identified DPR as a predictor of decreased survival (P = .002). CONCLUSION:Patients with a robust platelet count at day 100 are likely to do well. However, patients who do not experience a platelet count of ≥ 100 × 109/L have inferior long-term OS and DFS and may require further evaluation at the day 100 time point.