Omission of adjuvant chemotherapy in elderly patients with early stage breast cancer.

Abstract

12032 Background: Breast cancer incidence in elderly population over 70 years is anticipated to grow up to 35% by 2030. However, this elderly population is under-represented in the TAILORx (Trial Assigning Individualized Options for Treatment) with less than 5% of the entire study cohort. As the omission of radiation therapy among the elderly with favorable prognosis is a reasonable alternative option, omission of chemotherapy has not been prospectively investigated. To address this knowledge gap, we conducted an observational cohort study to evaluate the omission of chemotherapy in elderly patients with early breast cancer. Methods: The National Cancer Database (NCDB) was queried for patients above the age of 70 diagnosed with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, pT1-2N0 breast cancer who underwent hormone therapy with or without chemotherapy (2010-2015). Kaplan-Meier method and Cox multivariable analysis (MVA) were performed for survival analysis. Propensity score matching in a 1:1 ratio without any replacement was used to address selection bias. Sensitivity analysis was performed on a subgroup of those with a high 21-gene recurrence score (RS) > 25. Results: A total of 12004 patients were identified, including 10802 and 1202 patients with and without adjuvant chemotherapy, respectively. The median follow up was 38.2 months (IQR 22.5-57.2). On univariate analysis, chemotherapy was not associated with improved overall survival (HR 0.96, p = 0.71), ineligible for inclusion in the final MVA model. On interaction analysis, the use of chemotherapy had no interaction with RS (p = 0.46), age (p = 0.08), tumor size (p = 0.23), tumor grade (p = 0.42), and comorbidity score (p = 0.22). On 1030 and 689 matched pairs for all RS and RS > 25, respectively, there was no association of overall survival with chemotherapy (all RS: HR 0.76, p = 0.08; RS > 25: HR 0.74, p = 0.10). Conclusions: For elderly patients with early stage breast cancer, the addition of adjuvant chemotherapy may not be associated with improved survival even in the setting of high RS > 25. Given the toxicity profile of systemic therapy, shared decision making between clinicians and elderly patients is needed to individualize treatment options.