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 adapted stratification of disease 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 significance of WBC count, platelet counts, hemoglobin level and PETHEMA risk stratification system in Asian population and to propose new clinical prognostic system consisting of WBC counts, platelet counts and hemoglobin level.
Between 2000 and 2009, total of 156 consecutive patients with APL from 7 institutes in Republic of Korea were retrospectively reviewed. The patients received Idarubicin/ATRA based combination chemotherapy during remission induction, and consolidation therapy was given with idarubicin monotherapy or Idarubicin plus cytarabine. In the new 3 score prognostic model, WBC more than 10×109/L, platelet less than 40×109/L as well as hemoglobin less than 8g/dL were separately considered as an one risk factor, and patients having “0”, “1” and “2 or 3” risk factors fall into a score “0”, “1” and “2”, respectively.
With median follow-up of 3.8 years, the CR rate following remission induction treatment was 81.4% in overall patients (127 out of 156), and 24 (15.4%) were considered as failures due to early death (ED) within 30 days of APL diagnosis. The 4-year OS, LFS and CIR rate was 73.8±4.1%, 85.7±3.7, and 18.7±3.8%, respectively. Compared to the single variables such as WBC count, platelet count or hemoglobin level, the combined prognostic system such as PETHEMA stratification or CBC score provided better stratification for the prognosis in APL patients. The risk stratification system by PETHEMA could predict OS (p=0.014) and ED (p=0.024), but not CR rates or relapse. However, the proposed 3 score prognostic system could provide better stratification of APL patients in term of the CR rates (p=0.004), OS (p=0.004) and ED (p=0.008), but not of relapse risk.
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 ED, but not of the relapse risk. Prospective study with a single protocol will be needed to reach a clean conclusion of better clinical prognostic stratification of APL patients.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.