Anthropometric, medical history and lifestyle risk factors for myeloproliferative neoplasms in The Iowa Women's Health Study cohort

Classical myeloproliferative neoplasms (MPNs) are composed of essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis (MF), the etiology of which is largely unknown. We investigated the role of anthropometric, medical and lifestyle factors with risk of MPN in a prospective cohort of 27,370 women aged 55-69 years at enrollment. After >250,000 person-years of follow-up, 257 cases of MPN were identified (172 ET, 64 PV, 21 MF). Risk factor profiles were mostly unique for the two most common types, ET and PV. ET was associated with energy balance factors including body mass index (RR=1.52 for >29.3 vs. <23.4 kg/m(2); p-trend=0.042), physical activity (RR=0.66 for high vs. low; p-trend=0.04) and adult onset diabetes (RR=1.82; p=0.009), while PV was not. PV was associated with current smoking (RR=2.83; p-trend=0.016), while ET was not. Regular use of aspirin was associated with lower risk of ET (RR=0.68; p=0.017). These results broadly held in multivariate models. Our results suggest distinct etiologies for these MPN subtypes and raise mechanistic hypotheses related to obesity-related inflammatory pathways for ET and smoking-related carcinogenic pathways for PV. Regular aspirin use may lower risk for ET. What's New? Myeloproliferative neoplasms (MPNs) are diseases of the blood and bone marrow that include conditions such as essential thrombocythemia (ET) and polycythemia vera (PV). The risk factors and pathogenesis of MPNs, however, are largely unknown. In this investigation of medical, lifestyle, and anthropometric factors, obesity, physical inactivity, and adult onset diabetes were found to be associated with a higher risk of ET, whereas current smoking was associated with a higher risk of PV. Regular aspirin use, on the other hand, may lower ET risk. The findings suggest distinct etiologies for the most common MPN subtypes, ET and PV.