Adenoid Cystic Carcinoma of the Breast: An Oncological Center's Experience

Background: Adenoid cystic carcinoma of the breast (ACCB) is a rare breast malignancy. Despite often being a triple negative tumor, it has a favorable prognosis, with low rates of recurrence and progression. The ideal treatment of ACCB is debatable; thus, the aim of this study was to characterize a population diagnosed with ACCB and to evaluate the treatment outcomes. Methods: We performed a single-center retrospective analysis of patients with a histological diagnosis of ACCB treated at our dedicated Oncological Center between 1987 and 2020. The patients were identified in collaboration with the Anatomical Pathology Department, which also reviewed the surgical pathology reports. Results: Thirteen women with a median age of 68 years old were diagnosed with ACCB. The most frequent clinical diagnosis was a breast nodule (n=5); the preoperative image was suggestive of malignancy in nine patients, with seven being diagnosed with a ACCB in the preoperative biopsy. Regarding treatment, nine patients underwent conservative surgery, but three required re-excision. Sentinel lymph node biopsy (SLNB) was performed in seven patients, none revealing metastases; one patient had stage III ACCB and was initially treated with a modified radical mastectomy (MRM); the remaining were stage I (n=7) and II (n=5). Adjuvant radiotherapy was performed in eight patients, and two were initially proposed for chemotherapy but were considered unfit. With a median follow-up of 123 months (16-407), one case of local recurrence and two cases of distant metastasis were identified, one of whom died of disease. Conclusion: ACCB is a rare tumor with a good prognosis; however, as demonstrated, it can present an aggressive behavior. Conservative surgery and adjuvant radiotherapy are the indicated treatment and SLNB may be omitted in grade 1 tumors.