Aims: Use of multiparametric gene expression assays to identify patients who can avoid adjuvant chemotherapy without compromising on invasive breast cancer specific survival was supported by both RxPONDER and OPTIMA. We aimed to examine the clinicopathologic features and 5-year outcomes in patients that had Oncotype-DX testing for early breast cancer at our centre.
Methods: This was a retrospective institutional review of patients with HR+ early breast cancer who had an Oncotype-DX genomic assay with at least 5-years of follow-up at Chris O’Brien Lifehouse in Sydney, Australia. Data on baseline characteristics, recurrence score, adjuvant treatment and outcomes were collected.
Results: A total of 45 patients were identified with a median age at diagnosis of 53 years. Most patients had stage IIA (n=25, 56%) and lymph node negative (n=33, 73%) disease. In those undergoing adjuvant chemotherapy, median time to commencement from surgery was 52 days and only 1 patient (11%) commenced adjuvant chemotherapy within 6 weeks of surgery. Nodal and overall stage did not appear to correlate with recurrence score. Elevated Ki67 (≥14%) was more frequent in patients with high (n=4, 67%) and intermediate (n=10, 77%) recurrence scores. 4 of 6 patients (67%) with a high recurrence score received adjuvant tamoxifen and most of these patients (n=5, 83%) were post-menopausal. In pre-menopausal patients with an intermediate recurrence score, ovarian function suppression was used in 40% of patients. The 5-year distant recurrence-free survival was 97.8% in this cohort.
Conclusion: In our cohort, 83% of patients with node-positive disease were able to avoid adjuvant chemotherapy based on a low or intermediate recurrence score. An elevated proliferative index (Ki67 ≥14%) was observed more frequently in patients with an intermediate or high-risk score. Attention should be given to optimal care pathway adherence for timing of adjuvant chemotherapy given the potential risk of genomic test result delays.