title: Age-related incidence of cervical cancer supports two aetiological components: a population-based register study.
abstract: OBJECTIVE
  To assess whether age-related incidence of cervical cancer supports two aetiological components and to assess trends in these components due to risk factors and to organised screening in Finland.
  
  
  METHODS
  Population-based register study.
  
  
  METHODS
  Finnish Cancer Registry.
  
  
  METHODS
  Cervical cancer cases and female population in Finland in 1953-2012.
  
  
  METHODS
  Cervical cancer incidence was estimated using Poisson regression where age-specific incidence consists of two (early-age and late-age) normally distributed components.
  
  
  METHODS
  Accumulated net risks (incidences) and numbers of cancer cases attributed to each age-related component by calendar time.
  
  
  RESULTS
  The accumulated cervical cancer incidence in 2008-2012 was only 30% of that in 1953-1962, before the screening started. The fit of the observed age-specific rates and the rates based on the two-component model was good. In 1953-62, the accumulated net risk ratio (RR; early-age versus late-age) was 0.42 (95% CI 0.29-0.61). The early-age component disappeared in 1973-77 (RR 0.00; 95% CI 0.00-0.08). Thereafter, the risk for the early-age component increased, whereas the risk for the late-age component decreased, and in 2008-2012 the RR was 0.55 (95% CI 0.24-0.89).
  
  
  CONCLUSIONS
  In Finland, cervical cancer incidence has two age-related components which are likely to indicate differences in risk factors of each component. The trend in risk of both components followed the effects of organised screening. Furthermore, the risk related to the early-age component followed changes in risk factors, such as oncogenic HPV infections and other sexually transmitted diseases and smoking habits.
  
  
  CONCLUSIONS
  Cervical cancer incidence has two age-related components which are likely to have differencies in their aetiology.
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Seppä
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.|Department of Public Health, University of Helsinki, Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Pitkäniemi
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.|School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: N
authors.initials: N
authors.lastname: Malila
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.|School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Hakama
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D055088:Early Detection of Cancer; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D015233:Models, Statistical; D016012:Poisson Distribution; D012042:Registries; D012307:Risk Factors; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*
keywords: Age-related components; cervical cancer; incidence; time series 1953-2012