Atypical Ductal Hyperplasia on Percutaneous Breast Biopsy: Scoring System to Identify the Lowest Risk for Upgrade

Background: NCCN guidelines recommend surgical excision for patients with atypical ductal hyperplasia (ADH) on percutaneous biopsy. Improved imaging and biopsy techniques have lower contemporary upgrade rates, challenging standard practice. We sought to identify low-risk features of ADH to define patients who may benefit from active monitoring over surgical excision. Methods: A retrospective analysis identified 87 stereotactic biopsies diagnosing ADH undergoing surgical excision at a single institution from 01/2008 to 10/2015. Imaging was reviewed for lesion size and residual calcifications. Biopsy slides were reviewed for ADH features. Categorical variables were analyzed using Chi-square and Fisher’s exact tests; continuous variables with T- and Wilcoxon tests. Logistic regression model was used to determine the association between the number of low-risk features present and odds of upgrade. Results: Upgrade was identified in 13 cases (14.9%; 11 ductal carcinoma in situ and 2 invasive breast cancer). Low-risk imaging features included imaging size <1cm (P=0.004) and >50% removed by biopsy (P=0.03). The only significant low-risk pathologic feature was the lack of micropapillary features (P=0.10). Focal ADH (1-2 foci, P=0.12) was felt to be clinically significant. Those with the lowest risk of upgrade (0%) had all 4 low-risk features (n=17, 20%). When comparing biopsies that differed by one low-risk feature, the biopsy with one less low-risk feature present had 129% increase in odds of upgrade (exact OR=2.29, 95% CI 1.35, 4.15, P=0.001). Conclusion: Overall upgrade rate was low in this contemporary cohort. Patients at lowest risk for upgrade had all 4 low-risk features and could be safely offered active monitoring over surgical excision.