Research
Print page Print page
Switch language
The Capital Region of Denmark - a part of Copenhagen University Hospital
Published

Breast cancer mortality and overdiagnosis after implementation of population-based screening in Denmark

Research output: Contribution to journalJournal articleResearchpeer-review

  1. Induction of PIK3CA alterations during neoadjuvant letrozole may improve outcome in postmenopausal breast cancer patients

    Research output: Contribution to journalJournal articleResearchpeer-review

  2. Patterns in detection of recurrence among patients treated for breast cancer

    Research output: Contribution to journalJournal articleResearchpeer-review

  3. Ovarian removal at or after benign hysterectomy and breast cancer: a nationwide cohort study

    Research output: Contribution to journalJournal articleResearchpeer-review

  1. The accuracy of titanium contrast-enhanced mammography: a retrospective multicentric study

    Research output: Contribution to journalJournal articleResearchpeer-review

  2. Breast cancer survivors' risk of interval cancers and false positive results in organized mammography screening

    Research output: Contribution to journalJournal articleResearchpeer-review

  3. Impact of adding breast density to breast cancer risk models: A systematic review

    Research output: Contribution to journalReviewResearchpeer-review

  4. Impact of chronic diseases on effect of breast cancer screening

    Research output: Contribution to journalJournal articleResearchpeer-review

  5. Morbidity as a Predictor for Participation in the Danish National Mammography Screening Program: A Cross-Sectional Study

    Research output: Contribution to journalJournal articleResearchpeer-review

  • Elsebeth Lynge
  • Anna-Belle Beau
  • My von Euler-Chelpin
  • George Napolitano
  • Sisse Njor
  • Anne Helene Olsen
  • Walter Schwartz
  • Ilse Vejborg
View graph of relations

INTRODUCTION: Service breast cancer screening is difficult to evaluate because there is no unscreened control group. Due to a natural experiment, where 20% of women were offered screening in two regions up to 17 years before other women, Denmark is in a unique position. We utilized this opportunity to assess outcome of service screening.

MATERIALS AND METHODS: Screening was offered in Copenhagen from 1991 and Funen from 1993 to women aged 50-69 years. We used difference-in-differences methodology with a study group offered screening; a historical control group; a regional control group; and a regional-historical control group, comparing breast cancer mortality and incidence, including ductal carcinoma in situ, between study and historical control group adjusted for changes in other regions, and calculating ratios of rate ratios (RRR) with 95% confidence intervals (CI). Data came from Central Population Register; mammography screening databases; Cause of Death Register; and Danish Cancer Register.

RESULTS: For breast cancer mortality, the study group accumulated 1,551,465 person-years and 911 deaths. Long-term breast cancer mortality in Copenhagen was 20% below expected in absence of screening; RRR 0.80 (95% CI 0.71-0.90), and in Funen 22% below; RRR 0.78 (95% CI 0.68-0.89). Combined, cumulative breast cancer incidence in women followed 8+ years post-screening was 2.3% above expected in absence of screening; RRR 1.023 (95% CI 0.97-1.08).

DISCUSSION: Benefit-to-harm ratio of the two Danish screening programs was 2.6 saved breast cancer deaths per overdiagnosed case. Screening can affect only breast cancers diagnosed in screening age. Due to high breast cancer incidence after age 70, only one-third of breast cancer deaths after age 50 could potentially be affected by screening. Increasing upper age limit could be considered, but might affect benefit-to-harm ratio negatively.

Original languageEnglish
JournalBreast Cancer Research and Treatment
Volume184
Issue number3
Pages (from-to)891-899
Number of pages9
ISSN0167-6806
DOIs
Publication statusPublished - Dec 2020

ID: 61289492