B3 breast lesions determined by vacuum-assisted biopsy: how to reduce the frequency of benign excision biopsies.

Purpose: The aim of this study was to identify parameters allowing differentiation among the diverse group of B3 lesion at stereotactic vacuum-assisted biopsy (VAB) to identify patients with a low risk of cancer and who can therefore be referred for follow-up rather than surgery and thus reduce the number of unnecessary surgical procedures.

Materials And Methods: Among 608 VAB procedures performed for nonpalpable ultrasound (US)-occult mammographic abnormality, 102 cases of B3 were included in this study. Mammographic lesion type, lesion size, Breast Imaging Reporting and Data System (BIRADS) category, number of specimens per lesion and presence of atypia were retrospectively analysed. Results were compared with histological findings at surgery (53 cases) or mammographic findings during follow-up (49 cases). Statistical analysis was performed with univariate analysis (chi-square test), and statistical significance was set at p<0.05.

Results: The majority of cases were depicted as isolated microcalcifications (82.3%), were smaller than 10 mm (80.4%), had a low level of radiological suspicion (64.7%) and had 11 or more cores sampled (94.1%). Atypia at VAB was reported in 60 of 102 cases (58.8%). Carcinoma was found at excision in 5/60 (8%) B3 lesions with atypia and in no B3 lesions without atypia (p=0.146). Cancer at surgery was more frequent among cases of isolated microcalcifications (p=0.645), cases with high radiological suspicion (p=0.040) and those with a smaller number of cores sampled (borderline significant p=0.064).

Conclusions: On the basis of our experience, the presence or absence of atypia in our series proved to be the reliable criterion to prompt or avoid surgery in cases with a VAB finding of B3 lesion. This criterion may therefore be adopted in practice to more accurately select patients for surgery.