title: Effects of annual vs triennial mammography interval on breast cancer incidence and mortality in ages 40-49 in Finland.
abstract: BACKGROUND
  The aim of this study was to evaluate the effects of mammography screening invitation interval on breast cancer mortality in women aged 40-49 years.
  
  
  METHODS
  Since 1987 in Turku, Finland, women aged 40-49 years and born in even calendar years were invited for mammography screening annually and those born in odd years triennially. The female cohorts born during 1945-1955 were followed for up to 10 years for incident breast cancers and thereafter for an additional 3 years for mortality.
  
  
  RESULTS
  Among 14,765 women free of breast cancer at age 40, there were 207 incident primary invasive breast cancers diagnosed before the age of 50. Of these, 36 women died of breast cancer. The mean follow-up time for cancer incidence was 9.8 years and for mortality 12.8 years. The incidence of breast cancer was similar in the annual and triennial invitation groups (RR: 0.98, 95% confidence interval (CI): 0.75-1.29). Further, there were no significant differences in overall mortality (RR: 1.20, 95% CI: 0.99-1.46) or in incidence-based breast cancer mortality (RR: 1.14, 95% CI: 0.59-1.27) between the annual and triennial invitation groups.
  
  
  CONCLUSIONS
  There were no differences in the incidence of breast cancer or incidence-based breast cancer mortality between the women who were invited for screening annually or triennially.
authors.affiliation: University of Turku, Turku, Finland.
authors.forename: I
authors.initials: I
authors.lastname: Parvinen
authors.forename: S
authors.initials: S
authors.lastname: Chiu
authors.forename: L
authors.initials: L
authors.lastname: Pylkkänen
authors.forename: P
authors.initials: P
authors.lastname: Klemi
authors.forename: P
authors.initials: P
authors.lastname: Immonen-Räihä
authors.forename: L
authors.initials: L
authors.lastname: Kauhava
authors.forename: N
authors.initials: N
authors.lastname: Malila
authors.forename: M
authors.initials: M
authors.lastname: Hakama
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000401:mortality*; D055088:Early Detection of Cancer; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000379:methods*; D008875:Middle Aged; D013997:Time Factors