Additional value of fine-needle aspiration biopsy in a mammographic screening trial

The Stockholm breast cancer screening trial used single-view mammography as the sole screening method. A majority (63 per cent) of the mammographic selected cases from the first two screening rounds had uncertain mammograms, coded as 3 on an ordinal scale from 1 to 5, where 1 and 2 are dismissed as normal mammograms and 5 stands for a typical cancer. In this group of uncertain mammograms 30 cases were malignant and 431 were non-malignant. The aim of this study was to examine whether surgical biopsy in this group could be replaced by fine-needle aspiration (FNA) biopsy, combined with the information from the mammogram and clinical examination, and whether this diagnostic strategy could select the malignant cases with a high sensitivity. FNA biopsy selected 25 of the 30 mammary carcinomas as definite malignancy or atypia, with a sensitivity of 83 per cent (95 per cent confidence interval: 69-96 per cent), and combined with the information from the mammogram and clinical examination 29 of the malignancies were selected with a sensitivity of 97 per cent (95 per cent confidence interval: 83-100 per cent). In 398 of 431 non-malignant cases the diagnosis was established with the triple diagnostic approach without needing a surgical biopsy. In a clinical follow-up study, up to 64 months after the first screening round, only one false negative case was found, included in the group of 30 malignancies described above. With this strategy the rate of negative surgical biopsies was reduced by 90 per cent in the group with uncertain mammograms and without considerably impairing the reliability of the results.