Introduction
Needle core biopsy (NCB) is frequently used in assessing screen-detected breast lesions. Uncertainty remains over appropriate management of NCBs reported as 'uncertain malignant potential' (B3) or 'suspicious of malignancy' (B4). This study aims to analyse a large screening dataset to establish positive predictive values (PPVs) for malignancy on excision biopsy, for different classifications of B3 and for B4 NCBs.
Methods
Retrospective analysis was conducted of prospectively collected data for South East London Breast Screening Service. A total of 5,324 patients underwent NCB between 2000 and 2010, including 14G (ultrasound-guided) and 10G vacuum-assisted biopsies (stereo-guided). A total of 444 were B3 (8.3%) and 38 (0.7%) were B4. NCBs reported as B3 were classified by pathological subtype and PPVs for malignancy calculated for each subtype. Outcomes following B4 NCB were also assessed.
Results
The overall PPV for malignancy for B3 NCBs was 25% and for B4 NCBs was 74%. The PPVs for each subtype of B3 classification were as follows: papillary 14%, atypical intraductal epithelial proliferation 35%, phyllodes 11%, lobular 47%, complex sclerosing lesion/radial scar 6%, columnar cell 29%.
Conclusion
Our findings indicate that NCBs reported as B4 should be excised as they have a high likelihood of malignancy on excision biopsy. The PPVs for subtypes of B3 NCBs vary considerably. However, B3 subtypes with atypia should be treated with a higher level of suspicion and preferably be surgically excised. Decisions regarding further assessment should be made in a multidisciplinary setting.