Performance of 4 years of population-based mammography screening for breast cancer combined with ultrasound in Tyrol / Austria.

BACKGROUND: Systems for the delivery of screening mammography vary among countries and these differences can influence screening effectiveness. We evaluated the performance of organized mammography screening for breast cancer combined with ultrasound in Tyrol / Austria, an approach that differs from many other population-based screening programs.
METHODS: Data on women aged 40-69 years screened in the period from June 2008 to May 2012 were collected within the framework of an organized screening program. A total of 272,555 invitations were sent to the target population living in Tyrol and 176,957 screening examinations were performed. We analyzed the main performance indicators as defined by European Union (EU) guidelines and some important estimates of harms.
RESULTS: The estimated 2‑year participation rate was 56.9%. As ultrasound is implemented as second-line screening procedure, 76.2% of all women screened underwent supplementary ultrasound. In total 2322 women were recalled for further assessment (13.1 per 1000 screens) and 1351 biopsies were performed (7.6 per 1000 screens). The positive predictive value was 28.2% for assessment and 48.5% for biopsies. The cancer detection rate was 3.7 per 1000 screens and the proportion of all stage II+ screen-detected cancers was 35.5%. The interval cancer rate was 0.33 and 0.47 per 1000 screens in the first and second years, respectively. The estimated cumulative risk for a false positive screening result and an unnecessary biopsy for women following the invitation approach was 21.1% and 9.4%, respectively.
CONCLUSION: The performance of our population-based screening approach combining mammography and ultrasound is very favorable and potential harm is kept very low compared to other European mammography screening programs for breast cancer.