Abstract
Adjuvant chemotherapy (CT) is commonly recommended to breast cancer patients following surgery. However, not all patients benefit from it, and the intervention is associated with a substantial clinical burden, which also negatively affects quality of life. The aim of this symposium was to provide insights into the use of the 21-gene Oncotype DX® Breast Recurrence Score (RS) assay (Genomic Health Inc., Redwood City, California, USA) to optimise treatment decisions. The symposium started with an overview of the role of biomarkers in precision medicine in early breast cancer, provided by Prof Sparano, with a focus on recent developments in predicting CT benefit and assisting with the treatment decision-making based on the Oncotype DX® assay. CT is becoming a personalised medicine, comparable with oestrogen receptor (ER) expression testing and hormonal therapy, or human epidermal growth factor receptor (HER)2 testing and trastuzumab. Prof Sparano, the principal investigator of the TAILORx study, presented clinical trial and real-world evidence demonstrating a lack of CT benefit in approximately 80% of patients (those with RS results 0–25) and a substantial benefit in about 20% of patients (mainly those with RS results 26–100). This was brought into the perspective of clinical practice by Prof Penault-Llorca, who discussed the value of genomic assays versus classical pathological parameters and predictors of prognosis (e.g., age, ER and HER2 status, histological subtypes, Ki67 +/- mitotic index) and their associated risk of CT overtreatment and undertreatment. Prof Penault-Llorca also provided an insight into the lack of interchangeability of currently available genomic breast cancer tests. The symposium concluded with a presentation by Prof Nitz on CT decisions, specifically in node-positive breast cancer patients. Clinical and real-world data from large registries support CT decisions based on RS, independent of nodal status, to prevent overtreatment in daily routine.