Related Experiment Video
Updated: May 13, 2026
13:44
Detection of Architectural Distortion in Prior Mammograms via Analysis of Oriented Patterns
Published on: August 30, 2013
Overdiagnosis in screening mammography in Denmark: population based cohort study
Sisse Helle Njor1, Anne Helene Olsen, Mogens Blichert-Toft
1Department of Public Health, University of Copenhagen, Østre Farimagsgade 5, DK 1014 Copenhagen K, Denmark.
BMJ (Clinical Research Ed.)
|February 28, 2013
Summary
Mammography screening for breast cancer likely leads to 2.3% overdiagnosis, with excess incidence compensated after eight years. This study analyzed data from two population-based screening programs to assess overdiagnosis in mammography.
Area of Science:
- Oncology
- Radiology
- Public Health
Background:
- Population-based screening programs aim to detect cancer early.
- Mammography screening is a common method for breast cancer detection.
- Overdiagnosis, the detection of cancers that would not have become clinically apparent, is a concern in screening programs.
Purpose of the Study:
- To quantify the extent of overdiagnosis in mammography screening.
- To analyze breast cancer incidence trends in relation to screening programs.
- To determine the time required for incidence rates to normalize after screening cessation.
Main Methods:
- Population-based cohort study involving 57,763 women in Denmark.
- Comparison of breast cancer incidence between screened populations and historical/national control groups.
- Analysis of relative risks for breast cancer incidence during and after screening periods.
Main Results:
- Screening initiation caused prevalence peaks in breast cancer incidence (RR 1.84-2.06).
- Subsequent screening rounds showed relative risks slightly above unity (RR 1.04-1.14).
- Overdiagnosis was estimated at 2.3% (95% CI -3% to 8%) for targeted women and 1-5% for participants.
Conclusions:
- Mammography screening likely results in a small but significant rate of overdiagnosis.
- Excess breast cancer incidence due to screening is compensated for approximately eight years after screening ends.
- Further research is needed to refine overdiagnosis estimates and inform screening guidelines.
Related Concept Videos
01:29Bias in Epidemiological Studies
Biases can arise at various stages of research, from study design and data collection to analysis and interpretation. Recognizing and addressing these biases is essential to ensure the validity and reliability of epidemiological findings.Broadly speaking, biases in epidemiology fall into three main categories: selection bias, information bias, and confounding. A more detailed description of possible biases is:
01:25Imaging Studies for Cardiovascular System VI: Calcium -Scoring CT
Calcium-Scoring CT ScanA calcium-scoring CT scan, also known as coronary artery calcium (CAC) scan, detects calcium deposits in the coronary arteries. This test assesses the risk of coronary artery disease (CAD), which can lead to cardiovascular events such as angina, heart failure, and sudden cardiac arrest.A calcium-scoring CT scan is generally recommended for individuals at intermediate risk of CAD without symptoms. It includes:Men aged 40-75 and women aged 50-75: Especially those with a...