To report the findings of a six-year medial oudit performed at our mammographic screening centre, comparing those findings with the follow-up data stored at our hospital and at the Korea Central Cancer Registry.

We analyzed the findings of 32,289 mammographic examinations of 25,541 women performed at our screening center between 1994 and 1999. For follow-up and outcome monitoring, the guideline of the American College of Radiology Breast Imaging Reporting and Data System (ACR BI-RADS) was used. All mammograms were categorized by means of BI-RADS, and cases in categories 0, 4, and 5 were followed up through a review of our hospital information system. To determine whether any cases were false negative, we compared breast cancer patients registered in our medical record department and in the Korean Central Cancer Registry during the study period, with women whose mammograms were interpreted as normal or benign at our screening center within a year prior to cancer diagnosis.

The mean age of women enrolled in this study was 48.6 years, ten years less than reported in the West. The recall rate was 6.2%. Among 256 women whose final assessment category was 4 or 5, breast cancer was diagnosed in 51. The cancer detection rate was 2.0/1,000 women; positive predictive value 1 (PPV1: PPV, based on abnormal findings at screening examination) was 2.5% of cases and PPV2 (PPV when biopsy or surgical consultation was recommended) was 20%. The most common mammographic finding was microcalcifications only (45%). The rate of minimal breast cancer, including invasive cancer less than 1 cm in diameter and ductal carcinoma in situ, was 72.5%. Node positivity was 27%. Sensitivity was 85.0% based on the tumor registry of our institution's medical record department, and 78.5% based on the tumor registry of the Korea Central Cancer Registry. Specificity was 99.0%.

In our study, the cancer detection rate at screening mammography was 2.0/1,000 women. The rate of minimal breast cancer (72.5%) was very high but measurable sensitivity was 78.5%, somewhat lower than the ACR guideline of 85%. To improve the performance of screening mammography, appropriate interpretation of mammography and constant, follow-up and outcome monitoring are important.