ABSTRACT
BACKGROUND: Estimating distant recurrence risk in women with estrogen receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer is still challenging. EndoPredict® is a gene expression-based test predicting the likelihood of recurrent disease. We analyzed the difference in oncological decision making with and without the knowledge of gene expression tests. PATIENTS AND METHODS: This is a retrospective analysis including patients diagnosed with hormone-receptor positive, Her2 negative breast cancer between 2011 and 2015 at the Municipal Breast Cancer Centre Cologne, Germany. All patients received an evaluation by EndoPredict®. An oncological tumor board (TB) with knowledge of these results served as a baseline (control group). This baseline was compared to the treatment decision (adjuvant chemotherapy yes vs. no) made by oncologists with different experience levels (less than 5 years, between 5 and 15 years, and more than 15 years) who were not provided the EndoPredict® scores. All clinicians had access to clinical as well to histopathological data. RESULTS: There was no significant difference between control group and the oncologists with different experience levels concerning a chemotherapy indication. A trend could be shown in the subgroup of nodal negative patients between the treatment recommendation and physicians with more than 15 years of experience (p = 0.088). A further trend could be demonstrated in the subgroup of patients with a low Ki67 index (≤ 14%) (p = 0.063) between physician with 5-10 years of clinical experience and official treatment recommendation. CONCLUSION: It seems that inexperienced physicians may profit from the use of EndoPredict® to avoid an overtreatment. In nodal negative patients and patients with a low Ki67 index, undertreatment can be avoided with the use of EndoPredict® (borderline significance). Further prospective studies with larger study cohorts are needed to further validate this tool.
