title: Balancing the benefits and detriments among women targeted by the Norwegian Breast Cancer Screening Program.
abstract: To compute a ratio between the estimated numbers of lives saved from breast cancer death and the number of women diagnosed with a breast cancer that never would have been diagnosed during the woman's lifetime had she not attended screening (epidemiologic over-diagnosis) in the Norwegian Breast Cancer Screening Program.
  
  
  
  The Norwegian Breast Cancer Screening Program invites women aged 50-69 to biennial mammographic screening. Results from published studies using individual level data from the programme for estimating breast cancer mortality and epidemiologic over-diagnosis comprised the basis for the ratio. The mortality reduction varied from 36.8% to 43% among screened women, while estimates on epidemiologic over-diagnosis ranged from 7% to 19.6%. We computed the average estimates for both values. The benefit-detriment ratio, number of lives saved, and number of women over-diagnosed were computed for different scenarios of reduction in breast cancer mortality and epidemiologic over-diagnosis.
  
  
  
  For every 10,000 biennially screened women, followed until age 79, we estimated that 53-61 (average 57) women were saved from breast cancer death, and 45-126 (average 82) were over-diagnosed. The benefit-detriment ratio using average estimates was 1:1.4, indicating that the programme saved about one life per 1-2 women with epidemiologic over-diagnosis.
  
  
  
  The benefit-detriment ratio estimates of the Norwegian Breast Cancer Screening Program, expressed as lives saved from breast cancer death and epidemiologic over-diagnosis, should be interpreted with care due to substantial uncertainties in the estimates, and the differences in the scale of values of the events compared.
authors.affiliation: Department of Screening, Cancer Registry of Norway, Oslo, Norway Solveig.Hofvind@kreftregisteret.no.|Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway.
authors.forename: Solveig
authors.initials: S
authors.lastname: Hofvind
authors.affiliation: Department of Screening, Cancer Registry of Norway, Oslo, Norway.|National Advisory Unit for Women's Health, Oslo University Hospital, Oslo, Norway.
authors.forename: Marta
authors.initials: M
authors.lastname: Román
authors.affiliation: Department of Screening, Cancer Registry of Norway, Oslo, Norway.
authors.forename: Sofie
authors.initials: S
authors.lastname: Sebuødegård
authors.affiliation: Oslo Centre for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway.
authors.forename: Ragnhild S
authors.initials: RS
authors.lastname: Falk
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000401:mortality; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods; D008403:Mass Screening / Q000379:methods; D000069342:Medical Overuse / Q000706:statistics & numerical data*; D008875:Middle Aged; D009026:Mortality; D009664:Norway / Q000453:epidemiology; D017063:Outcome Assessment, Health Care
keywords: Breast neoplasms; breast cancer mortality reduction; false-positive results; mass screening; over-diagnosis