Background: Conventional wisdom suggests that a patient with a positive sentinel node requires a completion axillary clearance to obtain full staging and durable regional control. However, this dictum has been challenged by the recent American College of Surgeons Oncology Group Z0011 Trial demonstrating that women with node-positive breast cancer who underwent sentinel node biopsy only, and were treated with breast conserving surgery and radiation, had equivalent locoregional recurrence and survival rates to those who had a completion axillary clearance. The aim of our study was to determine what the clinical impact of the Z0011 findings might be if patients were managed according to the Z0011 criteria in an Australian teaching hospital setting. Methods: We performed a retrospective review, using prospectively collected data, of all female patients with breast cancer assessed at the Westmead Breast Cancer Institute in 2010 and identified the subgroup who would potentially have fulfilled all Z0011 criteria. The characteristics and management of this group were compared with node-positive and to mastectomy patient subgroups. Results: A total of 280 patients with invasive breast cancer were identified. Twenty-six patients satisfied all Z0011 criteria, representing 9.3% of all patients and 21.5% of node-positive patients. Twenty-two (84.6%) patients had a subsequent axillary clearance, with six (27.3%) having additional positive nodes. Conclusions: The Z0011 study is relevant to 9.3% of all breast cancer patients and 21.5% of node-positive breast cancer patients treated in a major Australian teaching hospital.

Introduction. The Oncotype DX test is a genomic assay that generates a Recurrence Score (RS) predicting the 10-year risk of recurrence and response to adjuvant chemotherapy in ER+/HER2− breast cancer patients. The aims were to determine breast cancer distant recurrence and correlate with adjuvant chemoendocrine prescribing patterns based on the Oncotype DX recurrence score. Methods. We conducted a retrospective single-institution case series of 71 patients who had Oncotype DX assay testing after definitive surgery between 2012 and 2016. Both node-positive and node-negative patients were included. Patients were divided into Oncotype DX low risk (RS < 11) (n = 10, 14%), intermediate risk (RS 11–25) (n = 45, 63%), and high risk (RS > 25) (n = 16, 23%). Median follow-up was 6.1 years (range 4–8.9 years). Adjuvant treatment regimens and oncological outcomes were determined. Results. Mean age at diagnosis was 56 years (range, 33–77). Invasive ductal carcinoma (IDC) accounted for the majority (87%), with most tumors measuring between 10–20 mm (52%). 48% of the cohort were node positive. 15 of 16 high-risk patients (94%) received chemotherapy. 96% of intermediate-risk patients received endocrine therapy alone, one patient received chemoendocrine therapy (2%), and one declined systemic therapy (2%). In the low-risk group, 100% received endocrine therapy only. The high-risk group had the lowest mean ER% ( ), greatest mean mitotic rate ( ), and greatest proportion of Ki67% > 14. Five patients developed distant recurrence (7%): three from the intermediate-risk group (7%), one from the low-risk group (10%), and one from the high-risk group (6%). Conclusion. This is the first Australian study reporting the experience with medium-term recurrence outcomes of using the Oncotype DX assay in breast cancer. Chemotherapy was rarely given for patients with low-to-intermediate RS and always offered in high RS. This pattern of prescribing was associated with low rates of distant recurrence. National funding models should be considered.