Treatment of adenoid cystic carcinoma of the breast: Is postoperative radiation getting its due credit?

INTRODUCTION: The role of postoperative radiation (PR) in treating mammary ACC is poorly defined. This study evaluated the impact of PR on survival outcomes for mammary ACC and the extent of utilization. METHODS: Patients who underwent surgery for mammary ACC from 2005 to 2015 in SEER database were analyzed. KM analyses of OS and DSS were done for PR versus no PR. Cox hazard regression models were used to determine predictors of OS and DSS. RESULTS: Of the 488 patients, 244 underwent PR. The PR group was younger, but other variables were similar between the 2 groups. OS was better for PR (p = 0.029). 10-year DSS was better for PR group by an absolute value of 6 % but did not reach statistical significance (p = 0.537). Age, radiation, nodal metastasis, and grade III/IV were independent predictors of OS while grade III/IV and AJCC stage III/IV independently predicted DSS. CONCLUSION: PR improves OS for mammary ACC, but this study did not show increased utilization. Radiation should be considered after surgery for mammary ACC, particularly for patients with independent predictors of OS.