title: Overdiagnosis due to breast cancer screening: updated estimates of the Helsinki service study in Finland.
abstract: BACKGROUND
  Overdiagnosis is the most important adverse event of breast cancer screening with the estimates ranging from 0% to 40-50% depending on invitational age and methods. We updated the estimates of overdiagnosis in Helsinki service screening study in Finland by comparing the observed and expected cumulative incidence of all breast carcinomas and invasive breast carcinomas.
  
  
  METHODS
  Women aged 50-59 years have been invited to Helsinki service screening since 1986. The incidence of breast carcinoma in the first invited birth cohorts born in 1935-1939 was compared with older, non-invited cohorts. The minimum follow-up time of the invitees after the last screening round was 14 years. Expected cumulative incidence rates were estimated with two alternative approaches.
  
  
  RESULTS
  For both any breast carcinoma and invasive breast carcinoma, the estimates of overdiagnosis varied from 5% (95% CI=-1, 11%) to 7% (95% CI=1, 13%) depending on the approach.
  
  
  CONCLUSIONS
  Our estimates of overdiagnosis are of the same magnitude than other plausible estimates in Europe. Both alternative approaches produced similar estimates for the expected cumulative incidence, which increased the confidence in the estimates of overdiagnosis.
authors.affiliation: Finnish Cancer Registry, Mass Screening Registry, Unioninkatu 22, 00130 Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Heinävaara
authors.affiliation: Finnish Cancer Registry, Mass Screening Registry, Unioninkatu 22, 00130 Helsinki, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Sarkeala
authors.affiliation: Finnish Cancer Registry, Mass Screening Registry, Unioninkatu 22, 00130 Helsinki, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Anttila
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis* / Q000453:epidemiology; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000175:diagnosis* / Q000453:epidemiology; D055088:Early Detection of Cancer; D005189:False Positive Reactions; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008327:Mammography; D008875:Middle Aged