Addition of Hemoglobin Level Into the Prognostic Scoring System Together with White Blood Cell and Platelet Count Provides Better Prognostic Stratification for Treatment-Related Mortality and Overall Survival, but Not for Relapse Risk In Adult Patients with Acute Promyelocytic Leukemia

Although the introduction of all-trans retinoic acid (ATRA) and combined chemotherapy improved clinical outcomes of acute promyelocytic leukemia (APL), treatment failure still occur due to early death or disease relapse. The PETHEMA study suggested that the risk adopted stratification of disease risk into 3 groups (low, intermediate and high risk) according to the white blood cell (WBC; 10×10⁹/L) and platelet counts (40×10⁹/L) could improve treatment outcomes of APL patients. However, this stratification system needs to be validated in an independent cohort of patients. The current study attempted to validate the prognostic system based on WBC and platelet counts, hemoglobin level, risk stratification system by PETHEMA and proposed prognostic system consisting of WBC and platelet counts and hemoglobin level.

Total of 164 patients was included retrospectively from 5 institutes in Republic of Korea. In patients receiving Idarubicin/ATRA based combination chemotherapy. Consolidation therapy was given with Idarubicin monotherapy in 79 patients, or Idarubicin plus cytarabine in 42 patients.

With median follow-up of 2.94 years, the CR rate following remission induction treatment was 83.9% in overall patients, while the 3 years OS, TRM and relapse rate was 77.6±3.5%, 20.4±3.3, and 9.6±3.1%, respectively. The combined prognostic system provided better stratification of APL patients according to their prognosis compared to single variable comparison such as WBC counts, platelet counts or hemoglobin level. In addition, the risk stratification system by PETHEMA could predict OS (p=0.06) and TRM (p=0.05), but not CR rates (p=0.1) or relapse (p=0.7). However, the proposed 3 score prognostic system could provide better stratification of APL patients in term of the CR rates (p=0.01 vs 0.1 between 3 score system vs PETHEMA risk stratification), OS (p=0.02 vs. 0.06) and TRM (p=0.006 vs 0.05), but not of relapse risk (p=0.9 vs 0.7).

This retrospective study suggested that the proposed 3 score prognostic system could provide better stratification of APL patients in term of the CR rates, OS and TRM, but not of relapse the risk. Further study will be needed to reach a clear conclusion of better prognostic stratification of APL patients with large number of patients.

No relevant conflicts of interest to declare.