title: Interval breast cancers in an Australian mammographic screening program.
abstract: OBJECTIVE
  To determine the incidence of interval cancers which occurred in the first 12 months after mammographic screening at a mammographic screening service.
  
  
  METHODS
  Retrospective analysis of data obtained by crossmatching the screening Service and the New South Wales Central Cancer Registry databases.
  
  
  METHODS
  The Central & Eastern Sydney Service of BreastScreen NSW.
  
  
  METHODS
  Women aged 40-69 years at first screen, who attended for their first or second screen between 1 March 1988 and 31 December 1992.
  
  
  METHODS
  Interval-cancer rates per 10000 screens and as a proportion of the underlying incidence of breast cancer (as estimated by the underlying rate in the total NSW population).
  
  
  RESULTS
  The 12-month interval-cancer incidence per 10000 screens was 4.17 for the 40-49 years age group (95% confidence interval [CI], 1.35-9.73) and 4.64 for the 50-69 years age group (95% CI, 2.47-7.94). Proportional incidence rates were 30.1% for the 40-49 years age group (95% CI, 9.8-70.3) and 22% for the 50-69 years age group (95% CI, 11.7-37.7). There was no significant difference between the proportional incidence rate for the 50-69 years age group for the Central & Eastern Sydney Service and those of major successful overseas screening trials.
  
  
  CONCLUSIONS
  Screening quality was acceptable and should result in a significant mortality reduction in the screened population. Given the small number of cancers involved, comparison of interval-cancer statistics of mammographic screening programs with trials requires age-specific or age-adjusted data, and consideration of confidence intervals of both program and trial data.
authors.affiliation: Department of Public Health and Community Medicine, Faculty of Medicine, University of Sydney, NSW. Mary@ces.bci.org.au
authors.forename: M T
authors.initials: MT
authors.lastname: Rickard
authors.forename: R J
authors.initials: RJ
authors.lastname: Taylor
authors.forename: M A
authors.initials: MA
authors.lastname: Fazli
authors.forename: N
authors.initials: N
authors.lastname: El Hassan
mesh_terms: D000328:Adult; D000368:Aged; D019985:Benchmarking; D001943:Breast Neoplasms / Q000401:mortality*; D002568:Certification; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D009517:New South Wales; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D011785:Quality Assurance, Health Care / Q000706:statistics & numerical data*; D016019:Survival Analysis