Canadian Journal of Public Health

, Volume 103, Issue 6, pp e420–e424 | Cite as

False-positive Screening Mammograms and Biopsies Among Women Participating in a Canadian Provincial Breast Screening Program

  • Andrew J. ColdmanEmail author
  • Norman Phillips
Quantitative Research


Background: Mammography screening results in false positives that cause anxiety and utilize scarce medical resources for their resolution. Determination of screening recommendations requires knowledge of the population risk of false positives.

Methods: Data were extracted from the Screening Mammography Program of British Columbia and analyzed to determine the influence of personal factors including age, ethnic group and screening history, and the centre where screening was performed, on the likelihood a new screen would result in a false positive and whether a biopsy was required. The resulting probabilities were combined to provide values for lifetime screening algorithms.

Results: Age, screen sequence number, history of previous abnormal screens and centre where screening was performed were significantly related to the likelihood a new screen would be a false positive. British Columbia women screened biennially between the ages of 50 and 69 have a projected 41% chance of a false-positive screen and a 5.6% risk of a related biopsy, with the best performing centres having rates of 26% and 3%, respectively.

Interpretation: Model projections for BC overall are comparable to other North American estimates. Estimates varied depending upon screening centre attended.


Contexte: Le dépistage mammographique donne des faux positifs qui causent de l’anxiété et dont la résolution exige le recours à des ressources médicales limitées. La décision de recommander ou non un dépistage nécessite une connaissance du risque de faux positifs dans la population.

Méthode: Nous avons extrait nos données du programme de mammographie de dépistage de la Colombie-Britannique et nous les avons analysées pour déterminer l’influence des facteurs individuels, dont l’âge, le groupe ethnique et les antécédents de dépistage, ainsi que du centre où le dépistage a lieu, sur la probabilité qu’un nouveau dépistage donne un résultat faussement positif et sur la nécessité d’une biopsie. Les probabilités résultantes ont été combinées pour produire les valeurs d’algorithmes de dépistage au cours de la vie.

Résultats: L’âge, le numéro de séquence du dépistage, les antécédents de dépistages anormaux et le centre où se fait le dépistage étaient significativement liés à la probabilité qu’un nouveau dépistage donne un faux positif. Selon nos projections, les femmes de la Colombie-Britannique dépistées tous les deux ans entre l’âge de 50 et de 69 ans ont une probabilité de 41 % d’avoir un dépistage faux positif et un risque de 5,6 % de subir une biopsie connexe; ces taux sont de 26 % et de 3 %, respectivement, dans les centres les plus performants.

Interprétation: Les extrapolations du modèle à l’ensemble de la Colombie-Britannique sont comparables à d’autres estimations nord-américaines. Les estimations varient selon le centre de dépistage fréquenté.

Key words

Mass screening mammography sensitivity and specificity breast neoplasms 

Mots clés

dépistage de masse mammographie sensibilité et spécificité tumeurs du sein 


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Copyright information

© The Canadian Public Health Association 2012

Authors and Affiliations

  1. 1.Cancer Surveillance and Outcomes, Population OncologyBC Cancer AgencyVancouverCanada

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