title: Estimating infra-national and national thyroid cancer incidence in France from cancer registries data and national hospital discharge database.
abstract: OBJECTIVE
  As in many countries, cancer registries cover only part of the population in France. Incidence/mortality ratio observed in registries is usually extrapolated to produce national estimates of cancer incidence. District-level estimates are not currently available. For cancer sites such as thyroid, the incidence/mortality ratio widely varies between districts, and alternative indicators must be explored. This study aims to produce national and district-level estimations of thyroid cancer incidence in France, using the ratio between incidence and hospital-based incidence.
  
  
  METHODS
  Analyses concerned population living in France and aged over 20, for the period 1998-2000. For each sex, number of incident cases were analysed according to number of surgery admissions for thyroid cancer (Poisson model) in the districts covered by a registry. Age was included in the model as fixed effect and district as random effect. The model's ability to predict incidence was tested through cross-validation. The model was then extrapolated to produce national incidence estimations, and for women, district-level estimations.
  
  
  RESULTS
  The national estimations of incidence rate age-standardised on the world population were 3.1 [95% prediction interval: 2.8-3.4] for men and 10.6 [9.8-11.4] for women, corresponding respectively to 1,148 [1,042-1,264] and 4,104 [3,817-4,413] annual new cases. For women, district-level incidence rates presented wide geographical variations, ranging broadly from 5 to 20 per 100,000. These estimations were quite imprecise, but their imprecision was smaller than the extent of geographical disparities.
  
  
  CONCLUSIONS
  National incidence estimations obtained are relatively precise. District-level estimations in women are imprecise and should be treated carefully. They are informative though regarding the extent of geographical disparities. The approach can be useful to improve national incidence estimates and to produce district-level estimates for cancer sites presenting a high variability of the incidence/mortality ratio.
authors.affiliation: Département des maladies chroniques et des traumatismes, Institut de Veille Sanitaire (InVS), 12 rue du Val d'Osne, Saint, Maurice 94415, France. z.uhry@invs.sante.fr
authors.forename: Zoe
authors.initials: Z
authors.lastname: Uhry
authors.forename: Marc
authors.initials: M
authors.lastname: Colonna
authors.forename: Laurent
authors.initials: L
authors.lastname: Remontet
authors.forename: Pascale
authors.initials: P
authors.lastname: Grosclaude
authors.forename: Nicolas
authors.initials: N
authors.lastname: Carré
authors.forename: Chantal Marie
authors.initials: CM
authors.lastname: Couris
authors.forename: Michel
authors.initials: M
authors.lastname: Velten
mesh_terms: D000368:Aged; D016208:Databases, Factual; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010351:Patient Discharge; D012042:Registries; D013964:Thyroid Neoplasms / Q000453:epidemiology*