Decisions On Adjuvant Chemotherapy For Patients With Breast Cancer Based On Clinical And Evolving Oncotype Dx Criteria.

e12009 Background: Oncotype-DX assay recurrence score (ODX-RS) cut-off values have recently changed in response to the results of the TAILOR-X trial. We aim to explore decisions for ACT based on physicians’ clinical assessment and on evolving ODX-RS. Methods: Patients who underwent ODX testing after curative surgical resection of estrogen receptor positive (ER+), Her2 non-over-expressed (Her2-) and lymph node negative (LN-) BC were included. Patients with micro-metastases to LNs were excluded. Data was collected retrospectively from the electronic records. Management of these patients was guided by the results of the old ODX-RS-1 (<18, 18-30 & ≥31) risk grouping. For the purpose of this study, treatment decisions were also assumed according to TAILOR-X results (ODX-RS-2). Decisions of 3 medical oncologists on ACT were solicited by blinding them to the RS values to investigate inter-physicians discrepancy and concordance with ODXA RS-1&2. Results: Sixty six consecutive patients fulfilled the inclusion criteria. Median age was 50.5 (range: 21-73) years. There was one male patient and 37 out of 65 females (56.9%) were pre-menopausal. Median tumor size was 21.5 (range: 10-55) mm and the grade were I, II and III in 6 (9.1%), 46 (69.7%) and 41 (21.2%) patients respectively. The 3 oncologists’ had discrepancies about ACT recommendations in 29 (44%) patients. Based on majority opinion (≥2 oncologists), ACT would have been recommended to 22/41 (53.7%) and 24/46 (52.2%) patients with low risk tumors according to ODXA RS-1 and ODXA RS-2 respectively. Similar number of patients (n=12) would have received ACT regardless of ODXA RS cut-off value (table). Conclusions: Decisions on ACT for patients with ER+/Her2-/LN- early BC should be guided by ODX-RS to prevent overtreatment and discrepancies in management. Broadly, ODXA RS-1 and ODXA RS-2 seem to guide ACT decisions in similar proportions of patients. Nevertheless minor differences exist and need to be studied in larger cohorts. [Table: see text]