PS1472 CURRENT PRACTICE IN THE MANAGEMENT OF ESSENTIAL THROMBOCYTEMIA AND POLYCYTHEMIA VERA: A SURVEY FROM THE FRENCH INTERGROUP OF MYELOPROLIFERATIVE NEOPLASMS (FIM) AMONG 120 HEMATOLOGISTS AND INTERNISTS

Background: The management of essential thrombocytemia (ET) and polycythemia (PV) is mainly based on experts’ recommendations. These recommendations have been revised these past few years (WHO criteria 2016, European Leukemia Net 2018), yet some aspects remain non‐consensual. Aims: We performed a survey to evaluate the current practice and the use of current recommendations among French speaking haematologists and internists regarding diagnosis and treatment for PV and ET; and their knowledge about these recommendations. Methods: A 35‐items questionnaire was sent by the FIM, the French Society of Haematology (SFH), and the French Society of Internal Medicine (SNFMI) mailing lists. All practitioners taking care of PV and ET patients were encouraged to answer. Results: We received 120 answers. 85% of the respondents are clinical Haematologists, 12% Internists, 3% Oncologists. 91% of them are working in France. All of them are used to treat PV and ET in their clinical practice, but 59% consider themselves as “non‐experts” for myeloproliferative neoplasms (MPN). Their qualification year as medical doctor ranges from 1974 to 2017 (median 2000). In our survey, the haemoglobin and haematocrit thresholds justifying the search for a polycythaemia in asymptomatic patients are very variable among respondents. The haemoglobin and haematocrit values used by most respondents for the diagnosis of PV do not seem to be strictly concordant with the WHO recommendations; many of them insist on taking into account the context. The search for JAK2 mutations is performed largely according to the recommendations, with JAK2 V617F in first intention, then either exon 12 mutations in case of suspicion of PV, or CALR and MPL mutations for the exploration of a non‐reactive thrombocytosis. The bone marrow biopsy is generally not considered mandatory or important for the diagnosis, neither of PV nor of ET – even if it is a major criterion in the WHO 2016 classification. Only 16% and 28% of the respondents perform a biopsy for all PV and ET patients. Most of clinicians (76% for PV, 68 % for ET) perform this biopsy only in selected cases, when the diagnosis is considered more difficult: suspicion of PV without JAK2 mutation or with limited elevation of haemoglobin, or “triple negative” thrombocytosis. An isotopic red cell mass measurement and/or an endogenous erythroid colony assay are still frequently performed (common practice for 90 % and 70 % of the respondents, respectively). The recommendations of initiating a cytoreductive treatment for patients with high thrombotic risk are largely respected. Of note, interferon‐alpha is frequently prescribed despite the lack of approval from the French medicine agency in MPN. In PV, 65% of practitioners use interferon‐alpha as first line therapy for patients younger than 40y and 45% for patients between 40 and 60y. In ET, 57% of the responders choose interferon‐alpha for high risk patients younger than 40y. Regarding antiplatelet agents, we observe heterogeneous practices without consensual indications of aspirin, particularly in terms of molecular status (JAK2 vs CALR) or platelet count. The objectives of treatment defined by the recommendations are mostly respected in PV; they are less strictly followed in ET. Summary/Conclusion: This study provides an overview of current “real life” diagnostic and therapeutic practices in PV and ET in France, which differ in several aspects from the international recommendations. These non‐consensual points may be discussed in future guidelines.