title: Improved breast cancer survival following introduction of an organized mammography screening program among both screened and unscreened women: a population-based cohort study.
abstract: BACKGROUND
  Mammography screening reduces breast cancer mortality through earlier diagnosis but may convey further benefit if screening is associated with optimized treatment through multidisciplinary medical care. In Norway, a national mammography screening program was introduced among women aged 50 to 69 years during 1995/6 to 2004. Also during this time, multidisciplinary breast cancer care units were implemented.
  
  
  METHODS
  We constructed three cohorts of breast cancer patients: 1) the pre-program group comprising women diagnosed and treated before mammography screening began in their county of residence, 2) the post-program group comprising women diagnosed and treated through multidisciplinary breast cancer care units in their county but before they had been invited to mammography screening; and 3) the screening group comprising women diagnosed and treated after invitation to screening. We calculated Kaplan-Meier plots and multivariable Cox proportional hazard models.
  
  
  RESULTS
  We studied 41,833 women with breast cancer. The nine-year breast cancer-specific survival rate was 0.66 (95%CI: 0.65 to 0.67) in the pre-program group; 0.72 (95%CI: 0.70 to 0.74) in the post-program group; and 0.84 (95%CI: 0.80 to 0.88) in the screening group. In multivariable analyses, the risk of death from breast cancer was 14% lower in the post-program group than in the pre-program group (hazard ratio 0.86; (95%CI: 0.78 to 0.95, P = 0.003)).
  
  
  CONCLUSIONS
  After nine years follow-up, at least 33% of the improved survival is attributable to improved breast cancer management through multidisciplinary medical care.
authors: The Cancer Registry of Norway, P,O,B 5313 Majorstuen, N-0304 Oslo, Norway. mette.kalager@kreftregisteret.no
authors: Mette
authors: M
authors: Kalager
authors: Tor
authors: T
authors: Haldorsen
authors: Michael
authors: M
authors: Bretthauer
authors: Geir
authors: G
authors: Hoff
authors: Steinar O
authors: SO
authors: Thoresen
authors: Hans-Olov
authors: HO
authors: Adami
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy; D002173:Cancer Care Facilities / Q000458:organization & administration / Q000706:statistics & numerical data; D015331:Cohort Studies; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008327:Mammography / Q000706:statistics & numerical data*; D019221:Mandatory Reporting; D008403:Mass Screening / Q000458:organization & administration / Q000706:statistics & numerical data*; D008875:Middle Aged; D009313:National Health Programs; D009664:Norway / Q000453:epidemiology; D015397:Program Evaluation; D016016:Proportional Hazards Models; D012042:Registries; D015996:Survival Rate