Incidence and Patient Survival of Myeloproliferative Neoplasms (MPNs) and Myelodysplastic/Myeloproliferative Neoplasms (MDS/MPNs) in the United States: A Population-Based View of the Modern Diagnostic Era

Introduction: Epidemiologic information on myeloproliferative neoplasms (MPNs) and myelodysplastic (MDS)/MPNs is largely derived from single institution and European population-based studies. Further, descriptive data encompassing the era of the World Health Organization classification (WHO) of hematopoietic neoplasms and JAK2 V617 mutation testing are sparse. Therefore, we utilized population-based data to comprehensively assess incidence and patient survival of MPNs and MDS/MPNs in the United States (US) during 2001-2012.

Methods: Using data from the National Cancer Institute's Surveillance, Epidemiology and End Results Program (SEER) Program, we assessed the incidence rates (IRs), IR ratios (IRRs), and 95% confidence intervals (CI) for each MPN and MDS/MPN entity. We assessed IRs overall and according to sex, race/ethnicity, calendar year of diagnosis, and method of diagnostic confirmation. We utilized the SEER*Stat Survival Session to calculate 5-year relative survival (RS) and 95% CI for each disease entity overall and according to sex and age at diagnosis.

Results: A total of 44,912 patients were diagnosed with MPNs and MDS/MPNs during 2001-2012. IRs were highest for polycythemia vera (PV) (n=10,812; IR=10.9 per 1,000,000 person-years) and essential thrombocythemia (ET) (n=9,394; IR=9.6). Except for ET and mastocytosis, the overall IRs for all entities were significantly higher among males than females, with male-to-female IRRs ranging from 1.4-2.3. PV incidence peaked in 2003-2004 and progressively decreased thereafter in contrast to IRs for ET which markedly increased after 2003-2004, with a suggestion of decrease after 2008. BCR-ABL1-positive chronic myelogenous leukemia (CML) IRs increased progressively over the study period while CML, NOS decreased over the study decade. All evaluable MPNs were associated with lower IRs among Hispanic whites than non-Hispanic whites (NHWs), with the exception of BCR-ABL1-positive CML, chronic eosinophilic leukemia (CEL), and juvenile myelomonocytic leukemia which occurred similarly among both groups. Except for CEL, Asians/Pacific Islanders had significantly lower MPN IRs than NHWs. ET, MPN-unclassifiable, and CEL IRs were 18%, 19%, and 60% higher, respectively, among blacks than NHWs. Among males and females, for all evaluable MPNs and MDS/MPNs, five-year RS was more favorable for younger (<60 years) than older (>60 years) individuals. Patients with PV or ET had the most favorable RS among both sexes and age groups, ranging from 92.0%-96.7% among those <60 years and 79.1%-87.9% among those >60 years. Patients with chronic neutrophilic leukemia, chronic myelomonocytic leukemia, and atypical BCR-ABL1 -negative CML patients had the least favorable 5-year RS (<35%). Females generally had more favorable survival than males, except for older males with PV who had significantly better survival than older women (RS IRR=1.08, 95%CI=1.03-1.13).

Conclusion: MPNs are a heterogeneous group of diseases and varying age, sex, and racial/ethnic incidence patterns support distinct etiologies and/or susceptible populations. The introduction of JAK2 V617 mutation testing in 2005 may have had a differential impact on IRs of PV and ET. Less favorable RS among older ages for all MPN subtypes suggests the need for inclusion of these individuals in clinical trials as new treatments become available.