gms | German Medical Science

Indroduction: The evaluation of the mammography screening is a part of the 'Guidelines for the Early Recognition of Cancer'. An important quality indicator is the frequency of interval cancers. It is to examine whether these breast cancers, which appear between two mammography screenings, could possibly have been discovered earlier. Another interest lies in the question, if thereare differences between interval cancers and screen-detected breast cancers (malignancy, tumour stage, histology). On identifying of interval cancers, the cancer registry of Lower Saxony (EKN) carries out a regular data matching with the Mammography Screening Projekt Weser-Ems (MSWE) [Ref. 1]. Interval cancers are compared to screen-detected breast cancers and to cases of a rural control region of Weser-Ems without organized screening.

Method: Approximately 22.600 women at the age of 50-69 are the population on whom the MSWE relates. The approx. 14.000 participants of the first screening round (5/2002-4/2004) are to analyse. On pseudonymous level, the data matching between EKN and MSWE takes place via control number system of the EKN.

Results: 21 interval cancers have been identified in the EKN until July 2005. Eight of them arose in the first year, thirteen in the second year after screening. In comparison with 112 screen-detected cases, the interval cancer t-stage distribution is unfavourable, but favourable to the control region of Weser-Ems. The proportion of very small interval cancers (smaller than 11 mm) and low malignant interval cancers is higher than expected, which is remarkable.

Discussion: For improvement the quality of the mammography screening and for early prediction of mortality reducing effects of screening, the frequency of interval cancers is important. In this study the results correspond to the EU-guidelines. To determine the real false-negative diagnoses, the following quality assurrance takes place in the MSWE. The medical review of the screening mammographies should be made, as well as the cause of diagnosis of interval cancer should be determined. Possibly some interval cancers appeared with women who have been recommended to participate to an early control mammography (early recall).