Gene-expression Profiling - A Decision Impact Analysis: Decision Dependency on Oncotype DX® as a Function of Oncological Work Experience in 117 Cases

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 (R) is a gene expression-based test predicting the likelihood of recurrent disease. This study analyzed the difference in oncological decision making with and without the knowledge of gene-expression tests based on oncological work experience. Materials and Methods: This was a retrospective analysis including n=113 patients diagnosed with hormone receptor-positive, HER2-negative breast cancer between 2011 and 2015 at the Municipal Breast Cancer Center Cologne, Germany. All 113 patients underwent evaluation by OncotypeDX (R). An oncological Tumor Board with knowledge of these results served as baseline (control group). This baseline was compared to the treatment decision for adjuvant chemotherapy 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 (R) results. Results: Inexperience led to a significant increase in recommendations for chemotherapy, with those made by the Tumor Board being least frequent (41.6% vs. <5 years=55.6%, 5-15 years=50.4%, and >15 years=42.5%; p<0.05). An exploratory subgroup analysis showed the Tumor Board was significantly less likely to recommend chemotherapy for patients with Ki67 >14%, pN1 and postmenopausal status than were oncologists with up to 15 years experience, with a strong trend for those with tumor size larger than pT2. Conclusion: With a maximum reduction of 14.2% for those with the lowest level of oncological experience, the likelihood of recommending chemotherapy was found to decrease with increasing oncological work experience. A subgroup analysis showed that differences in decision making were most likely in patients with a Ki67 >14%, tumor sizes larger than pT2, pN1 and postmenopausal patients. It is the opinion of this study group that gene-expression testing is especially pertinent for these subgroups.