Thrombocytosis Phenotype in Prefibrotic Primary Myelofibrosis: Risk Stratification and Prognostic Significance

Area of Science:

• Hematology
• Oncology

Background:

• Essential thrombocythemia (ET), prefibrotic primary myelofibrosis (pre-PMF), and overt primary myelofibrosis (PMF) are myeloproliferative neoplasms.
• These conditions share clinical features but differ in prognosis.
• The prognostic significance of thrombocytosis in pre-PMF requires investigation.

Purpose of the Study:

• To evaluate the prognostic impact of thrombocytosis in patients with pre-PMF.
• To compare survival outcomes between ET, pre-PMF, and overt PMF.
• To identify risk factors for mortality in pre-PMF.

Main Methods:

• Retrospective analysis of 350 myeloproliferative neoplasm patients diagnosed between 2002 and 2023.
• WHO criteria used for diagnosis.
• Overall survival analyzed with Cox models; competing-risk methods for complications (leukemic transformation, thrombosis, bleeding).

Main Results:

• Thrombocytosis in pre-PMF was associated with a significantly higher risk of death (HR 4.33, P = .045).
• Constitutional symptoms (aHR 10.81, P = .001), leukocytosis (aHR 7.69, P = .004), and thrombocytosis (aHR 7.80, P = .015) were independent prognostic factors for worse survival in pre-PMF.
• Overt PMF showed a significantly higher risk of death compared to pre-PMF without thrombocytosis (HR 2.80, P = .030).

Conclusions:

• Thrombocytosis is a significant adverse prognostic factor in pre-PMF, impacting overall survival.
• Platelet count serves as a practical tool for risk stratification in pre-PMF.
• Distinguishing pre-PMF from ET and overt PMF is clinically important due to differing prognoses.