Multivariate model to identify women at low risk of cancer upgrade after a core needle biopsy diagnosis of atypical ductal hyperplasia

Purpose: Atypical ductal hyperplasia (ADH) identified on percutaneous breast biopsy represents a high-risk lesion, upgrading to cancer with surgical excision in ~7–45.8% of cases. Routine excision is questioned due to potential overtreatment and cost. This study evaluates clinical, imaging, and histologic features to predict the risk of upgrade. Methods: With IRB approval, a single-institution retrospective review was performed of patients who underwent surgical excision of ADH diagnosed by core biopsy from June 2005 to June 2013. We reviewed electronic medical records, breast imaging, and biopsy slides. Multiple imputation was used for missing data. Association of various features with cancer upgrade was assessed using logistic regression. Results: Among 399 cases, the upgrade rate to cancer was 16.0%, (95% CI: 12.8–20.0%), with nine invasive cancers and 55 ductal carcinoma in situ (DCIS) only. Via a logistic regression approach, we defined a subgroup with low risk for upgrade: women whose biopsies showed no individual cell necrosis, and either a) 1 focus of ADH with ≥50% removal, or b) 2–3 foci with ≥90% removal. Cases meeting these criteria had an upgrade rate of 4.9% (95% CI: 1.0–8.9%), compared to 21.4% (16.4–26.3%) in cases that did not meet this low-risk definition. Conclusions: ADH on core biopsy with low risk of upgrade to cancer is defined by lack of individual cell necrosis, number of foci of ADH, and percent of imaging lesion removed. If these findings are validated, women whose biopsies meet low-risk criteria might be considered for prevention therapy and surveillance without surgical excision.