Abstract PO3-20-11: Among the &lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma
Authors: Choi Sera , Keshwani Sarah , Madrigrano Andrea 
Published: May 2024

Among the &lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma Sera Choi, B.A., Sarah Keshwani, M.D., Andrea Madrigrano, M.D. Introduction: Adenoid cystic carcinoma in the breast (ACCB) is a rare subtype of breast cancer that accounts for &lt; 0.1% of all breast-related malignancies. The majority of ACCB cases in existing literature are comprised of estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor 2 negative, abbreviated as triple-negative breast cancer. Although most triple negative breast cancers are aggressive in nature and prognosis, ACCB is reported to be more indolent with a favorable outcome. This disparity raises the question of whether the treatment approach for ACCB should follow the well-established treatment plan for other triple negative breast cancers given its atypical characteristics. Furthermore, while adenoid cystic carcinoma of the salivary glands is a well-known type of head and neck cancer with established treatment guidelines, there is limited data for recommendations regarding treatment for ACCB. We report a pathologically confirmed case of ACCB and review the existing literature regarding treatment strategy and prognosis. Case: This case is of a 69-year-old female who presented with an abnormal screening mammogram with a core needle biopsy confirming ACCB in the left lower outer quadrant. The patient was asymptomatic with no palpable masses, nipple discharge, or skin changes of the breast. Biopsy revealed adenoid cystic carcinoma grade 2, classic type, with immunochemistry confirming estrogen-receptor negative, progesterone-receptor negative, and human epidermal growth factor-receptor negative. After a thorough discussion of the options, the patient elected for breast conserving therapy and sentinel lymph node biopsy. Tumor was resected with negative margins and two out of two lymph nodes were negative for metastasis. The patient was recommended whole breast adjuvant radiation therapy given the large tumor size of 4.8cm. Chemotherapy was not recommended due to data that largely supports local targeted therapy over systemic treatment in patients without metastatic ACCB. The patient is continuing with routine follow-up evaluations. Discussion: Currently, mainstay treatment comprises of surgical resection with lumpectomy or mastectomy, with or without nodal evaluation. Radiation therapy is seen as beneficial in reducing recurrence and prolonging disease-free survival in ACCB. There is ongoing debate regarding the role of chemotherapy in ACCB patients, as triple-negative breast cancers are typically treated with a systemic chemotherapy regimen. However, since ACCB has a more favorable prognosis, the role of chemotherapy remains uncertain. With lack of data on ACCB, treatment modalities should be evaluated on a case-by-case basis. Moreover, considering the scarcity of information concerning this particular subtype of breast cancer, it is advisable to discuss these patients within a multi-disciplinary tumor board setting to ensure patients receive the maximum benefit.

Citation Format: Sera Choi, Sarah Keshwani, Andrea Madrigrano. Among the &lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-20-11.