False-negative breast screening assessment. What lessons can we learn?

AIM: To review women who have had breast cancer diagnosed following previou s assessment of a screen-detected mammographic abnormality in order to asce rtain the frequency and characteristics of false-negative assessment. MATERIALS AND METHODS: The assessment process was reviewed in the study pop ulation of 28 women. This included the nature of the lesion recalled for as sessment, additional mammography, clinical and ultrasound findings, and the results of fine needle aspiration cytology and needle histology. RESULTS: The frequency of false-negative assessment was approximately 0.56% . The median time between false-negative assessment and diagnosis of breast cancer was 33 months. The most common mammographic lesion resulting in fal se-negative assessment was micro-calcification seen in 12 cases (43%). Only five of these 12 cases had image-guided biopsy, the remainder were thought to be benign on magnification views. Other mammographic abnormalities were nine masses (32%), five architectural distortions (18%) and two asymmetric densities (7%). Of the 16 women with mammographic lesions other than micro -calcifications 10 had a normal ultrasound. CONCLUSION: Radiological interpretation of indeterminate micro-calcificatio ns as benign or malignant is unreliable. An isolated cluster of micro-calci fication requires image-guided core biopsy with representative micro-calcif ication obtained on specimen radiography, Further mammography done at asses sment, particularly paddle compression views, should be carefully analysed to ensure areas of architectural distortion have truly resolved. If one ima ging modality shows a significant abnormality and another does not the case s must be managed an the basis of the (C) 2001 The Royal College of Radiolo gists.