EPR22-111: Outcomes and Utilization of Adjuvant Chemotherapy With and Without an Anthracycline in Node-Positive, Triple-Negative Breast Cancer: Analysis of SEER-Medicare Data

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  • 1 University of Colorado Anschutz Medical Campus, Aurora, CO

Background: Triple-negative breast cancer (TNBC) is a subtype of breast cancer associated with an aggressive clinical course. Adjuvant chemotherapy has led to improved survival and decreased risk of recurrence with anthracycline and taxane therapy (ATAX) regimens shown to be more efficacious compared to non-anthracycline-containing, taxane-based regimens (TAX) in node-positive disease. However, data investigating outcomes and utilization of adjuvant chemotherapy in older women with node-positive TNBC remain to be explored. Methods: Using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we identified 1,106 women with node-positive, TNBC diagnosed at age > 65 between 2010-2015. We compared patient and clinical characteristics according to adjuvant chemotherapy regimen (ATAX versus TAX). Logistic regression was performed to estimate the odds ratios (OR) and 95% confidence intervals (CIs). Kaplan Meier survival curves were generated to estimate three-year overall survival (OS) and cancer specific survival (CSS). Cox proportional hazards models were used to analyze OS and CSS while controlling for patient and tumor characteristics. Results: Of the 1,106 patients in our cohort, 767 (69.3%) received adjuvant chemotherapy with the majority of patients receiving a taxane-containing regimen (ATAX or TAX), 661(86.1%). Patients with more extensive lymph node involvement (4 or more) were more likely compared to patients with 1-3 positive lymph nodes to receive ATAX versus TAX (OR 1.68, 95% CI [1.16, 2.44], p=0.006). Other independent predictors of ATAX versus TAX were age and non-cardiac co-morbidities. Three-year OS and CSS for patients who received ATAX versus TAX were similar at 74.2% versus 72.7% (p=0.79) and 82.8% versus 83.7% (p=0.80), respectively. There was a trend towards improved OS and CSS in patients with 4 or more lymph nodes involved among patients who received ATAX vs TAX (HR 0.69, 95% CI [0.41-1.15], p=0.15 and HR 0.67, 95% CI [0.36 – 1.24) p=0.20), respectively. Conversely, among patients with 1-3 lymph nodes involved who received ATAX versus TAX, there was a trend towards worse OS and CSS (HR 1.29, 95% CI [0.81-2.08], p=0.29 and HR 1.71, 95% CI [0.85 – 3.45) p=0.13). Conclusion: Among older women with node-positive TNBC, a majority of patients received adjuvant chemotherapy with the most common regimen being ATAX. Younger age, higher stage, and lack of co-morbidities correlated with the use of ATAX compared to TAX.

Corresponding Author: Stephanie Lakritz, MD
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