The Digital Breast Tomosynthesis (DBT) in the Oslo Mammography Screening Program will include women aged 50 to 69 years invited to the population-based mammography-screening program. All women attending the screening unit will be asked if they want to attend the trial. If so, they will be informed about the project, the technique, and the additional compression and radiation dose. All mammographic examinations of women attending the trial will be independently interpreted by four radiologists. Since the trial is part of the official Norwegian Breast Cancer Screening Program (NBCSP), the interpretations will be carried out on-line into the national screening database of the NBCSP. The study will include independent reading of conventional digital (2D) mammograms, 2D plus computer-aided detection (CAD), 2D plus DBT, and synthetic 2D plus DBT. There will be a common consensus meeting for all examinations having a positive score. Recalls and diagnostic work-up will be according to daily practice at the Oslo University Hospital Ullevaal and the guidelines of the NBCSP.

Outcome measures will use performance indicators for organized screening programs, including recall rate, false positive scores, cancer detection rate, positive predictive values, and cancer characteristics for the individual readers of the trial.

Inclusion Criteria:

• Women 50 to 69 years who have signed the informed consent

Exclusion Criteria:

• Women with pacemaker, implants, and severely disabled

Women aged 50 to 69 years attending the national breast cancer screening program who sign an informed consent regarding participation in the trial