Improved breast cancer survival following introduction of an organized mammography screening program among both screened and unscreened women: a population-based cohort study

Breast Cancer Res. 2009;11(4):R44. doi: 10.1186/bcr2331. Epub 2009 Jul 6.


Introduction: 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.

Publication types

  • Comparative Study
  • Controlled Clinical Trial
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Breast Neoplasms / diagnostic imaging*
  • Breast Neoplasms / mortality
  • Breast Neoplasms / therapy
  • Cancer Care Facilities / organization & administration
  • Cancer Care Facilities / statistics & numerical data
  • Cohort Studies
  • Early Diagnosis*
  • Female
  • Follow-Up Studies
  • Humans
  • Kaplan-Meier Estimate
  • Mammography / statistics & numerical data*
  • Mandatory Reporting
  • Mass Screening / organization & administration
  • Mass Screening / statistics & numerical data*
  • Middle Aged
  • National Health Programs
  • Norway / epidemiology
  • Program Evaluation
  • Proportional Hazards Models
  • Registries
  • Survival Rate