2888. Management of Screening-Detected Radial Scars in the Era of Digital Breast Tomosynthesis
Authors * Denotes Presenting Author
  1. Claire Crowley *; Harvard Medical School; Massachusetts General Hospital
  2. Manisha Bahl; Harvard Medical School; Massachusetts General Hospital
Radial scars are more frequently detected on digital breast tomosynthesis (DBT) than digital 2D mammography (DM), which has led to questions regarding appropriate management of radial scars in the current era of DBT. Previous studies about radial scars were performed in the era of DM and reported upgrade rates of mixed radial scars (associated with other high-risk pathology on biopsy), not “pure” radial scars. The purpose of this study is to determine the pathologic upgrade rates of pure and mixed radial scars detected on screening DBT and to identify mammographic features that may contribute to the risk of upgrade.

Materials and Methods:
In this Institutional Review Board-approved and Health Insurance Portability and Accountability Act-compliant study, medical records were reviewed of consecutive women who presented for screening DBT from January 1, 2013, to June 30, 2020, and were subsequently diagnosed with a radial scar by image-guided core needle biopsy. Included patients underwent surgical excision or had at least two years of imaging follow-up. Medical records were reviewed for imaging features, biopsy pathology results, and surgical pathology results. Upgrade rates of pure versus mixed radial scars were compared using the Pearson’s chi-squared test.

Of 153 patients with screening DBT-detected radial scars, 141 patients (92.2%) underwent surgical excision (79.4%, 112/141) or had at least two years of follow-up imaging (20.6%, 29/141). These 141 patients (mean age 56 years, range 29-83 years) comprised our study cohort. The overall upgrade rate of radial scars to malignancy (ductal carcinoma in situ [DCIS] or invasive malignancy) was 4.3% (6/141). The upgrade rate of pure radial scars to malignancy was 1.7% (2/117), and the upgrade rate of radial scars associated with atypical ductal hyperplasia (ADH), lobular carcinoma in situ (LCIS), or atypical lobular hyperplasia (ALH) to malignancy was 16.7% (4/24) (p<0.001). Five radial scars (two pure and three with associated atypia) were upgraded to DCIS, while one radial scar (with associated atypia) was upgraded to invasive ductal carcinoma. The upgrade rates based on mammographic features were 8.3% (1/12) for masses, 5.3% (4/75) for architectural distortion, 5.0% (1/20) for asymmetries, and 0% (0/34) for calcifications.

The risk of upgrade of screening DBT-detected pure radial scars to malignancy is low at 1.7%. Surveillance rather than surgical excision of pure radial scars may be a reasonable option, especially in patients with screening-detected calcifications that led to the image-guided biopsy and radial scar diagnosis. These results support American Society of Breast Surgeons guidelines, which state that imaging follow-up may be reasonable for incidental radial scars detected by imaging.