AB150. SOH22ABS120. Surgical management of estrogen receptor positive breast cancer in the West of Ireland

Background: Estrogen receptor positive (ER+) breast cancer accounts for 70–80% of new diagnoses. The cornerstone of breast cancer management involves surgical resection, with judicious use of chemoendocrine and radiotherapies.

Methods: Consecutive female patients with ER+ breast cancer managed in a single institution between 2005–2015 were included. Descriptive statistics were used as appropriate to outline clinicopathological and treatment data. Survival analyses were performed using Cox regression and log-rank Kaplan-Meier analyses.

Results: A total of 2,304 patients were included with a median age of 58.0±12.1 years (range, 21–95 years). Median follow-up was 98.2 months. Overall, 69.2% of patients underwent breast conserving surgery (BCS) (1,595/2,304) and 30.8% underwent mastectomy (709/2,304). Furthermore, sentinel lymph node biopsy was performed in 1,322 of cases (57.4%) and axillary lymph node dissection in 982 cases (42.6%). Older age at diagnosis (P=0.006), increased tumour size (P<0.001), grade 3 disease (P<0.001) and nodal status (P<0.001) were all associated with mastectomy. Patients undergoing BCS had enhanced disease-free survival (DFS) and overall survival (OS) (both P<0.001) than those undergoing mastectomy. Patients undergoing mastectomy had worse DFS [hazard ratio (HR): 2.739, 95% confidence intervals (CIs): 2.189–3.427, P<0.001] and worse OS (HR: 2.003, 95% CIs: 1.616–2.482, P<0.001).

Conclusions: The surgical management of breast cancer depends on routine clinicopathological parameters, such as patient age, tumour grade and tumour and axillary staging. In ER+ breast cancers, BCS remains the gold standard where feasible.

Keywords: Breast cancer; personalised medicine; precision oncology; surgery; surgical oncology