How effective is the German mammography screening program? This is the question examined by Oliver Heidinger of the Epidemiological Cancer Registry North Rhine–Westphalia and his co-authors in the first study on this subject in Germany, in Deutsches Ärzteblatt International (Dtsch Arztebl Int 2012; 109(46): 781-7).
To answer it, the authors have used the interval cancer rate as an indicator. Interval cancers are tumors found more or less by chance between two screenings. In approximately 880 000 women from North Rhine–Westphalia who had taken part in mammography screening for the first time between 2005 and 2008 and had received negative test results, the authors examined whether breast cancer occurred in the following 24 months. It was shown to occur in approximately 2000 women. This corresponds to a rate of 0.23%, a result that is absolutely comparable with similar international studies.
However, the authors also noticed another result in their follow-up research: 40% of all malignant breast tumors of size T2 to T4 (i.e. ranging from at least 2 cm to more than 5 cm) detected in the study participants during the observation period proved to be interval cancers. Further research is needed to explain this phenomenon.
http://www.aerzteblatt.de/pdf.asp?id=132482