Upgrade rate to malignancy of uncertain malignant potential breast lesions (B3 lesions) diagnosed on vacuum-assisted biopsy (VAB) in screen detected microcalcifications: Analysis of 366 cases from a single institution.

PURPOSE: We retrospectively investigated clinical, radiological, and pathological features of B3 lesions associated with the risk of subsequent upgrade to malignancy.

METHODS

We included consecutive vacuum-assisted biopsies (VABs) performed during 2011-2020 on suspicious microcalcifications not associated with other radiological signs diagnosed as B3 lesions and followed by surgical excision (SE) with definitive histological examination. Multiple logistic regression models were fitted to identify independent predictors of malignancy.

RESULTS

Out of the 366 B3 lesions included, 56 (15.3 %, 95 % CI 11.8-19.4 %) had upgraded to malignancy at SE: of these, 42/366 (11.5 %, 95 % CI 8.4-15.2 %) and 14/366 (3.8 %, 95 % CI 2.1-6.3 %) were in situ and invasive carcinoma, respectively. At univariate analysis, variables positively associated with upgrade to malignancy were age ≥ 60 years (p = 0.008), mixed morphology (p = 0.018), scattered distribution (p = 0,001), extension of microcalcifications > 10 mm (p = 0.001), and mixed B3 lesion (p = 0.017). Among B3 subtypes, the highest rates of upgrade were observed for AIDEP, LCIS/LIN2, FEA + AIDEP, FEA + LCIS/LIN2, and FEA + AIDEP + LCIS/LIN2 (24.6 %, 21.4 %, 25.3 %, 20.0 % and 40.0 % respectively), while FEA and ALH/LIN1 had a lower rates of upgrade (7.5 % and 3.7 %, respectively). Multiple logistic regression analysis confirmed as risk factors older age (p = 0.029), larger extension (p = 0.001) and mixed morphology (p = 0.007) of microcalcifications, AIDEP (p = 0.011) among pure B3 lesions, and FEA + AIDEP (p = 0.001) and FEA + AIDEP + LCIS/LIN2 (p = 0.037) among mixed B3 lesions.

CONCLUSIONS

Based on our findings, vacuum-assisted excision is reasonable as definitive management for FEA and ALH/LIN1, while SE should remain the mainstay of treatment for AIDEP and LCIS/LIN2, whose upgrade rates are too high to safely recommend VAE.