Rare thyroid malignancies in Europe: Data from the information network on rare cancers in Europe (RARECAREnet).

Limited information is available on the incidence of rare thyroid cancer (TC) subtypes: anaplastic (ATC) and medullary (MTC). The aim of this study was to describe incidence variations and trends across European countries of all TC subtypes. We used the RARECAREnet database including 80721 TC incident cases in the period 2000-2007 from 77 population-based cancer registries (CRs) in Europe. In the trend analyses, we included 68890 TC cases from 53 CRs with at least 6 years of incidence data in the years 2000-2007. In Europe age-standardised incidence rates (ASR) in women were The huge increase and heterogeneity between countries of PTC incidence has a small influence on the trends and variations of MTC and ATC in Europe. Large-scale epidemiological and clinical registry-based studies are warranted to increase knowledge about the rarest TC subtypes. This information would be fundamental for the design of new clinical trials and for inference