Oncotype DX score in hormone receptor-positive/HER2-positive breast cancer: A SEER analysis.

Abstract

e12044 Background: The recurrence score Oncotype DX (RS) predicts the need for adjuvant chemotherapy in hormone receptor positive (HR+) early stage breast cancer (BC). However, it has not been validated for HR+/HER2+ BC cases. We aim to evaluate the results of RS in HR+/HER2+ BC by using the Surveillance, Epidemiology, and End Results Program (SEER) national database. Methods: We identified patients with non-metastatic HR+/HER2+ BC with reported RS scores from the national SEER database between 2010 and 2015. Data obtained included demographics, histologic subtypes, grading, tumor size, nodal status, HR status and overall survival (OS) outcomes. RS scores were divided into low/intermediate (≤30) and high ( > 30). Histologic subtypes were further categorized into favorable (lobular, tubular, mucinous, and cribriform) and unfavorable (infiltrating ductal, mixed ductal, and micropapillary). We used Kaplan-Meier & Cox regression to analyze the survival outcomes. Logistic regression analysis was used to analyze the correlation between variables and different RS scores. Results: A total of 1537 patients were included. Median age was 61 (25-90). Majority of the patients presented with node negative disease (85%), low/intermediate grade (71%), tumor size < 20 mm (73%), unfavorable histology (89%), and only 15% had negative progesterone receptor (PR –). High RS score ( > 30) was seen in 24% of cases. After a median follow-up of 38 m (1-72), the five-year OS was 94.5%. Chemotherapy was given to 71% and 35% of those with RS > 30 and ≤30, respectively. There was a strong correlation between age > 60 ([hazard ratio, HR] = 4.9, p < 0.0001) and RS > 30 (HR = 2.4, p = 0.004) with worse outcomes on multivariate analysis. However, there were no associations between histologic subtype, tumor size, grade, nodal status and chemotherapy with survival. Tumor size > 20 mm (OR = 1.5), unfavorable histology ([odds ratio, OR] = 3.5), PR – (OR = 4.3) and high grade tumors (OR = 4.5) were independent predictors of RS > 30 (p < 0.0001). Conclusions: Our study shows that large tumor size ( > 20 mm), higher grade, PR –, and unfavorable histology were independent risk factors for higher RS in patients with localized early stage HR+/HER2+. High RS was associated with worse outcome.