AIMS: Treatment for Ductal Carcinoma in Situ (DCIS) includes surgery followed by radiotherapy (RT) to reduce local recurrence (LR) risk, though RT may be overtreatment for some patients. The Oncotype DX Breast DCIS Score® test is a genomic test that provides individualised LR risk estimates. This study evaluates the impact of the Oncotype test on RT recommendations, patient anxiety and decisional conflict. MATERIAL AND METHODS: Women aged ≥45 years with DCIS up to 25mm treated with breast-conserving surgery were invited to participate. Initial RT recommendations and 10-year LR risk predictions were made before Oncotype testing. Post Oncotype testing, final RT recommendations were recorded. Patients completed decisional conflict and anxiety questionnaires before and after receiving Oncotype results. RESULTS: A total of 71 participants were included with a median age of 59. Ninety percent of DCIS was intermediate/high-grade with a median size of 12mm. Oncologists changed RT recommendations in 28% (20/71) of cases after receiving the Oncotype result
21% changed from RT to no RT and 7% from no RT to RT. In 79% of cases, the oncologists' LR estimates were higher than Oncotype predictions. Post Oncotype testing, patient decisional conflict and anxiety decreased. CONCLUSION: The Oncotype test changed treatment recommendations regarding adjuvant RT in almost a third of patients. Additionally, the assay was associated with reduced treatment-related decisional conflict and anxiety in patients. LR risk predictions by oncologists were higher than the Oncotype predictions highlighting a need for additional tools to aid decision-making.