e12014 Background: Oncotype-DX Assay is a 21-gene based recurrence score (RS) that helps stratify breast cancer patients based on their risk of recurrence. It is often used to help identify patients that may benefit from adjuvant chemotherapy (AC). Prior to the TAILORx Trial results, there were no guidelines for AC in patients with an intermediate score (18-30). Management of these patients was often at the clinical judgement of the provider. We sought to determine predictors of AC among these patients, and measure treatment effect on survival. Methods: We queried the Surveillance, Epidemiology, and End-Results database for breast cancer patients newly diagnosed between 2010-2015. We included patients with T1-T3, hormone receptor positive, HER2-negative, and lymph node-negative breast cancer with an intermediate RS. Male patients, those younger than 40 years, tumors 5 mm or less, and incomplete records were excluded. Univariate and multivariate analysis was performed to derive independent predictors of AC. Cox Proportional-Hazards Model was done to examine the effect of AC on survival. Results: We included 14,710 patients of whom 4,508 (30.6%) received AC. Patients that received AC were younger (55.4 years [8.8] vs 60.0 [9.7], p < 0.001), grade III or higher (29.8% vs 16.4%, p < 0.001), and had a higher RS (23.9 [3.6] vs 21.5 [3.1], p < 0.001). Higher T stage was associated with a higher rate of patients receiving AC (p < 0.001). Marital status was also associated with AC; a higher proportion of patients who received AC were married (67.9% vs 64.4%, p < 0.001). There was no significant association between race/ethnicity or insurance type with AC. Multivariate analysis showed that RS (OR: 1.24 [1.23-1.26], p < 0.001), T stage (OR: 1.67 [1.21-2.30], p < 0.001), and a grade III tumor (OR: 1.85 [1.64-2.09], p < 0.001) were the strongest predictors of AC. The age decile 80-89 years (OR: 0.05 [0.02-0.10], p < 0.001) was the most negative predictor of AC. AC did not have an effect on 5 year overall survival (97.6% vs 96.0%, p = 0.28). Conclusions: Between 2010-2015, our study shows 30.6% of breast cancers patients with an intermediate Oncotype-DX score were given AC. The decision to treat was largely based on tumor size, grade and age. AC had no effect on overall survival.
Practice Patterns and Outcomes for Postmastectomy Radiation After Complete Pathological Response in Stage II and IIIA Breast Cancer Patients: Analysis of the National Cancer Data Base
