A Greek Real-World Experience With the Implementation of the EndoPredict Gene Signature in a Cohort of Pre-menopausal and Post-menopausal Patients With ER+/HER2- Breast Cancer.

Background EndoPredict® is a guideline-recommended gene signature assay guiding whether adjuvant treatment should include chemotherapy or not. The EndoPredict® Clinical (EPclin) Risk Score combines molecular and clinical data to predict the distant recurrence of breast cancer, providing valuable information about the prognosis and chemotherapy benefit in both pre- and post-menopausal patients. Methodology This is a real-world, retrospective study aiming to characterize the EPclin Risk Score's utility in 200 consecutively selected Greek patients with estrogen receptor positive/human epidermal growth factor receptor 2 negative (ER+/HER2-) breast cancer, enrolled in a single institution, considering their clinicopathological features and menopausal status, with emphasis on its role in identifying patients suitable for treatment de-escalation. Results In this study, 100 pre-menopausal and 100 post-menopausal ER+/HER2- breast cancer patients were included. Among the pre-menopausal subgroup, 65% of the patients were classified as low risk and the other 35% as high risk, while among the post-menopausal subgroup, the low-risk and high-risk patients were 66% and 34%, respectively. A notable 30% of node-positive premenopausal patients were characterized by EPclin as at a low risk of breast cancer. Conclusions The EPclin Risk score has the ability to stratify and guide therapy decisions in ER+/HER2- breast cancer patients. It classifies the recurrence risk differently from traditional assessments and identifies low-risk premenopausal patients with node-positive disease. This may provide a de-escalation treatment pathway for such patients but requires further clinical validation.