Incidence of acute promyelocytic leukemia across Europe: results of RARECAREnet-a population-based study.

The scarcity of studies performed over the past decades in Central and South America provided clues that the prevalence of acute promyelocytic leukemia (APL)-a rare and distinct subtype of acute myeloid leukemia-might be higher among descendants of Spaniards, as compared to other ethnic groups. Currently, a comprehensive apprehension on APL incidence across Europe has yet been established. Therefore, we conducted a population-based study to assess the incidence of APL across Europe. We selected all patients diagnosed with APL in Europe from the RARECAREnet database that holds data from 94 cancer registries across 27 European countries on rare malignancies diagnosed during 2000-2007. Age-standardized incidence rates (ASRs) with 95% confidence intervals (CIs) were calculated for the European pool per 100,000 person-years. Also, crude incidence rates with 95% CIs were calculated per 100,000 person-years by country. Overall, 1,876 patients with APL (48% male and 24% aged ≥65 years) were included in our analytic cohort. The overall ASR of APL was 0.112 (95% CI, 0.107-0.117) in Europe. The incidence of APL varied considerably across Europe, with the highest incidence in Spain (0.257; 95% CI, 0.205-0.317), as compared to the European average. Altogether, these finding adds additional support to the hypothesis that APL might be more prevalent among individuals with Spanish ancestry. Future research is warranted to specifically explore etiologic factors of APL across different genetic and environmental backgrounds.