Radial Scars on Screening Digital Breast Tomosynthesis: Upstaging Rates and Management Strategies.

Background: Radial scars are more commonly identified on digital breast tomosynthesis (DBT) than on digital mammography (DM). Nonetheless, universal guidelines for radial scar management in the current era of DBT are lacking. Objective: To determine the upstaging rates of screening DBT-detected radial scars with and without atypia and to identify features related to upstaging risk. Methods: This retrospective study included patients who underwent core-needle biopsy (CNB) showing a radial scar after screening DBT and DM from January 1, 2013, to December 31, 2020. Patients without surgical excision or at least 2 years of imaging follow-up after CNB were excluded. Rates of upstaging to breast cancer [ductal carcinoma in situ (DCIS) or invasive disease] were compared between radial scars with and without atypia at CNB. Associations of upstaging with patient, imaging, and pathologic variables were explored using standard statistical tests. Results: Of 165 women with 171 radial scars, the final study sample included 153 women (mean age, 56 years; range, 33-83 years) with 159 radial scars that underwent surgical excision (80.5%, 128/159) or at least 2 years of imaging follow-up (19.5%, 31/159). Seven radial scars were upstaged to DCIS and one to invasive disease. Therefore, the upstaging rate of radial scars to cancer was 5.0% (8/159). The upstaging rate of radial scars without atypia at CNB was 1.6% (2/129) and of radial scars with atypia was 20.0% (6/30) (p<.001). On multivariable analysis, features associated with higher upstaging risk included a prior breast cancer diagnosis (62.5% vs 4.8%, p=.01) and the presence of atypia at CNB (75.0% vs 15.9%, p=.02). The upstaging rate according to mammographic finding type was 7.1% (1/14) for asymmetries, 6.7% (1/15) for masses, 6.3% (6/96) for architectural distortion, and 0.0% (0/34) for calcifications. Conclusion: Screening-detected radial scars without atypia at CNB have a low upstaging rate to breast cancer of 1.6%. Clinical Impact: Imaging surveillance rather than surgery is a reasonable approach for radial scars without atypia, particularly for those presenting as calcifications.