Predictors of Invasive Breast Cancer in Patients With Ductal Carcinoma In Situ in Ultrasound-Guided Core Needle Biopsy

Objectives To determine predictors of invasiveness of lesions with US-guided biopsy-confirmed ductal carcinoma in situ (DCIS), focusing on US features, including shear wave elastography (SWE). Methods From January 2015 to September 2016, a total of 80 lesions with US-guided biopsy-confirmed DCIS were detected in patients who underwent preoperative mammography, B-mode US, and SWE. Data were retrospectively reviewed from clinical records, pathologic reports, and imaging assessments. Imaging data included mammographic findings, B-mode US findings based on the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS), and the mean and maximum elasticity values on SWE. The final BI-RADS assessment, including the degree of elasticity of the mass, was evaluated. Continuous variables were examined by an independent t test, and categorical variables were examined by the Fisher exact test. The independent factors for predicting a histologic upgrade were evaluated by a multivariate logistic regression analysis. Results Among the 80 lesions, 27 (33.8%) showed an invasive component after surgical excision. None of the BI-RADS US descriptors, which include shape, orientation, margin, and echogenicity, showed a significant correlation with the rate of a histologic upgrade to invasive cancer. However, the BI-RADS assessment category (P = .015) and nuclear grade (P = .005) were significantly correlated with invasiveness of the mass. The maximum stiffness value was lower in the pure DCIS group (119.04 vs 85.33 kPa; P = .041). Conclusions The BI-RADS category based on US findings, maximum stiffness value on SWE, and nuclear grade of DCIS are predictive of invasive components in DCIS.