Lifestyle factors and risk of myeloproliferative neoplasms in the NIH-AARP diet and health study.

The etiology of Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) is largely unknown. We assessed potential associations between lifestyle factors and MPN risk in the NIH-AARP Diet and Health Study. In this prospective cohort with 463,049 participants aged 50-71 years at baseline (1995-1996) and a median follow-up of 15.5 years, we identified 490 MPN cases, including 190 with polycythemia vera (PV) and 146 with essential thrombocythemia (ET). Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Smoking was not associated with MPN risk in the overall cohort, but analyses stratified by sex suggested that smoking increased the risk of MPN in women (former smoker vs. nonsmokers, HR = 1.43, 95% CI: 1.03-2.00, p = 0.03; current smokers vs. nonsmokers, HR = 1.71, 95% CI: 1.08-2.71, p = 0.02). Coffee consumption was inversely associated with the risk of PV (high vs. low intake, HR = 0.53, 95% CI: 0.33-0.84, p-trend < 0.01), but not the risk of ET or MPN overall. Further analysis revealed an inverse association between the amount of caffeine intake and PV risk (high vs. low intake, HR = 0.55, 95% CI: 0.39-0.79, p-trend < 0.01). While the consumption of caffeinated coffee appeared to confer a protective effect against PV, the consumption of decaffeinated coffee did not. This large prospective study identified smoking as a risk factor for MPN in women and suggests that caffeine intake is associated with a lower risk of PV.