Adenoid cystic carcinoma of the breast: molecular markers, treatment, and clinical outcome.

BACKGROUND: The objective of this study was to comprehensively characterize the clinical and biologic features of adenoid cystic carcinoma (ACC) and to assess the implications for management in a large cohort of patients.

METHODS: From a database of 50,000 patients, 28 were identified with ACC for which clinical follow-up and biologic information was available. The biologic features examined included estrogen receptor and progesterone receptor status, DNA ploidy, and S-phase fraction. Median follow-up was 83 months with a range of 29 to 144 months. Overall survival and disease free survival curves were drawn using Kaplan and Meier estimates and were compared by the log-rank test.

RESULTS: All but one patient were postmenopausal with a median age at diagnosis of 66 years (range, 40-96 years). One patient had macroscopic metastatic disease at diagnosis. Median tumor size was 1.9 cm (range, 0.5-7.0 cm). Axillary lymph node dissection was performed in 23 patients. Only 1 patient (4%) had histologic positive lymph nodes (2 of 10), and no recurrence was detected for this patient. Forty-six percent were ER positive (median, 16 fmol/mg protein; range, 5-1017 fmol/mg), and 35% were PgR positive (median, 61 fmol/mg protein; range, 6-854 fmol/mg). S-phase fraction and DNA ploidy were assessable in 24 cases. Ninety percent of tumors had low S-phase (median, 3.3%; range, 0.1-34.2%), and 92% were diploid. Simple or modified radical mastectomy was performed in 22 patients, and 6 patients were treated by lumpectomy. Five of these six patients also received radiation therapy after lumpectomy. Despite the different surgical approaches, there were no local recurrences. The 5-year disease free survival rate was 100%, and the 5-year overall survival rate was 85% (95% confidence interval, 71.7-98.6%).

CONCLUSIONS: Adenoid cystic carcinomas of the breast have very favorable biologic characteristics and, consistent with this, an excellent prognosis. Good local control can be achieved by lumpectomy with radiation or by simple mastectomy. Axillary lymph node dissection is not helpful in clinical management.