Abstract P4-08-21: Gene expression profiling – a decision impact analysis – Decision dependency on OncotypeDX and EndoPredict as a function of oncological work experience
Authors: Eichler C , Fromme J , Puppe J , Malter W , Paepke S , Warm M 
Published: May 2019

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. Oncotype DX and EndoPredict are two competing, gene expression-based tests predicting the likelihood of recurrent disease. We analyzed the difference in oncological decision making with and without the knowledge of gene expression tests.
Methods: We performed a retrospective, analysis including n = 192 patients diagnosed with G2, HR+, Her2- breast cancer between 2011 and 2015 at the Municipal Breast Cancer Centre Cologne, Germany. All 192 patients received an evaluation by OncotypeDX or EndoPredict. An oncological tumor board (TB) with knowledge of these results served as baseline (control group). This baseline was compared to the treatment decision (adjuvant chemotherapy Yes vs. No) reached 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 OncotypeDX or EndoPredict scores. All clinicians had access to clinical as well to histopathological data only.
Results: Within the EndoPredict group no significant decrease between overall TB decision (adjuvant chemotherapy Yes) 48.1% vs. 15+ years = 39.2%, 5-15 years = 39.2% and &lt;5 years = 50.6% group could be shown. Endopredict seemed to overestimate the clinical risk as judged by experienced oncologists. Within the OncotypeDX cohort we were able to find a significant decrease between overall TB decision (chemotherapy Yes) 41.6% vs. 15+ years = 42.5%, 5-15 years = 50.4% and &lt;5 years = 55.6% group (p&lt;0.05). In addition, inexperience led to a significant and numerically greater increase in chemotherapy recommendation. An exploratory subgroup analysis showed significant differences in TB vs oncologist decision for Ki67 &gt;14%, tumor sizes larger than pT2, pN1 and postmenopausal patients for all experience levels.
Conclusions: Overall, results for the EndoPredict group were inconclusive. A significant reduction of chemotherapy recommendation was shown for all experience levels in the Oncotype subgroup however, with a maximum reduction of 14.2%. A subgroup analysis showed that differences in decision making were most likely for patients with a Ki67 &gt;14%, tumor sizes larger than pT2, pN1 and postmenopausal patients. Since these are the patients where the question of pro/contra chemotherapy is most important, it is the opinion of this study group that gene expression testing is especially pertinent for these patients.
Citation Format: Eichler C, Fromme J, Puppe J, Malter W, Paepke S, Warm M. Gene expression profiling – a decision impact analysis – Decision dependency on OncotypeDX and EndoPredict as a function of oncological work experience [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-21.