title: The impact of a two- versus three-yearly cervical screening interval recommendation on cervical cancer incidence and mortality: an analysis of trends in Australia, New Zealand, and England.
abstract: OBJECTIVE
  To assess the impact of cervical screening interval recommendations on cervical cancer incidence and mortality during periods of organized and opportunistic screening in Australia (2-yearly screening interval for organized screening), New Zealand (3 yearly interval for organized screening), and England (3/5 yearly interval for organized screening).
  
  
  METHODS
  Changes in cervical cancer rates over two 10-year periods were assessed in each country among women aged 20-69 years using a standardized rate ratio (SRR). The SRR for opportunistic screening was calculated from 1973-1977 to 1983-1987 (mortality only), and for organized screening from 1993-1997 to 2003-2007 (mortality and incidence).
  
  
  RESULTS
  During the period of opportunistic cervical screening, mortality reduced by 24% in Australia and 10% in England and Wales [Australia: SRR 0.76 (95% CI 0.71-0.83); England and Wales: SRR 0.90 (95% CI 0.87-0.93)]; no statistically significant reduction was observed in New Zealand [SRR 0.95 (95% CI 0.82-1.11)]. After the introduction of organized screening, mortality reduced 39-45% in each country [Australia: SRR 0.56 (95% CI 0.51-0.62); New Zealand: SRR 0.53 (95% CI 0.44-0.63); England and Wales: SRR 0.61 (95% CI 0.58-0.64)], while incidence reduced 19-38% [New Zealand: SRR 0.62 (95% CI 0.56-0.69); Australia: SRR 0.64 (95% CI 0.61-0.72); England: SRR 0.81 (95% CI 0.78-0.83)].
  
  
  CONCLUSIONS
  In the era of opportunistic screening, some reductions were observed in cervical cancer mortality rates, but these were relatively modest and seen inconsistently between countries. After the introduction of organized cervical screening, cervical cancer mortality rates fell by a similar amount (~40% or more) in all countries, and incidence fell by more than a third in Australia and New Zealand and by approximately one-fifth in England. Although several factors are likely to have influenced these observed reductions in cervical cancer rates, these findings do not support the more frequent 2-yearly cervical screening interval recommendation in Australia.
authors.affiliation: Cancer Epidemiology Research Unit, Cancer Council NSW, 153 Dowling Street, Woolloomooloo, Sydney, NSW 2011, Australia. leosimonella@gmail.com
authors.forename: Leonardo
authors.initials: L
authors.lastname: Simonella
authors.forename: Karen
authors.initials: K
authors.lastname: Canfell
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D055088:Early Detection of Cancer / Q000379:methods* / Q000706:statistics & numerical data* / Q000639:trends; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D009520:New Zealand / Q000453:epidemiology; D016019:Survival Analysis; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D055815:Young Adult