The Utility of the Oncotype DX Test for Breast Cancer Patients in an Australian Multidisciplinary Setting.

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% (P < 0.05), greatest mean mitotic rate (P < 0.05), 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.

Effect of the American College of Surgeons Oncology Group Z0011 trial on axillary management in breast cancer patients in the Australian setting.

The American College of Surgeons Oncology Group Z0011 Trial demonstrated that early breast cancer patients with positive axillary sentinel lymph nodes treated with breast-conserving surgery and breast radiotherapy had no additional oncologic benefit of proceeding to an axillary lymph node dissection (ALND). The extent to which practice has changed in Australia remains unclear. The aim of this study was to investigate the effect of the Z0011 trial on the management of positive axillary sentinel nodes at an Australian institutional level. We reviewed all breast cancer cases treated at the Sydney Adventist Hospital over a 10-year period from 1 January 2008 to 31 December 2017. Patients who fulfilled the Z0011 trial criteria were selected. These patients were divided into two groups according to the year of surgery, before and after 1 January 2011 when the Z0011 study was published. Clinicopathologic data and axillary surgical management were compared. Of the 237 patients fulfilling the Z0011 trial criteria, there were 73 patients before and 158 patients after 1 January 2011. In the earlier group the rate of proceeding to an ALND following a positive sentinel node was 78.1% compared to 43.7% in the latter group (P < 0.0001). There was a significant decline in the rate of ALND over this 10-year period (r = -0.79, P = 0.006). The Z0011 trial has influenced the surgical management of the axilla leading to a significant reduction in the rate of an ALND in patients fulfilling the Z0011 trial criteria at our institution.