Abstract PO3-03-08: Use of adjuvant Capecitabine after neoadjuvant chemotherapy: A Cohort Study among Elderly Patients with Early-Stage Triple-Negative Breast Cancer
Authors: Sullivan Marija , Lei Xiudong , Malinowski Catalina , Giordano Sharon , Chavez Marianna 
Published: May 2024

Abstract
Background: The use of capecitabine in the adjuvant setting in patients with residual disease after neoadjuvant chemotherapy has been incorporated into practice based on the results of the CREATE-X trial. We evaluate utilization patterns of adjuvant capecitabine use, its association with outcomes, and subsequent hospitalizations and emergency room (ER) visits among elderly patients with early-stage triple-negative breast cancer (TNBC).
Methods: We identified patients aged ≥66, diagnosed with early-stage TNBC between 2010 and 2017 in the SEER and Texas Cancer Registry (TCR)-linked Medicare databases. All patients were treated with neoadjuvant chemotherapy for localized or regional-stage disease. All patients had continuous enrollment in Medicare Parts A & B without a Health Maintenance Organization enrollment 12 months before cancer diagnosis and 12 months after cancer diagnosis. Chemotherapy administration was identified using HCPCS codes from outpatient and physician’s carrier claims. We analyzed the patterns of capecitabine use, its association with survival outcomes, and the frequency of ER visits and hospitalizations during treatment (between the first capecitabine claim and 30 days after the last claim for capecitabine). Descriptive statistics were used. Primary analyses included logistic regression, Kaplan-Meier estimates, and Cox regression models with propensity score adjustments. This study adhered to the STROBE guidelines for cohort studies.
Results: 1,239 patients with localized or regional TNBC treated with neoadjuvant chemotherapy were included (median 72 years). Of them, 96 (7.7%) were prescribed adjuvant capecitabine. Treatment with capecitabine was associated with recent year of diagnosis, regional disease, and residing in non-metropolitan areas. Specifically, the use of capecitabine increased from 1% in 2010 to 10% in 2016 and 21% in 2017. The median duration of capecitabine treatment was 4 cycles. In multivariable logistic regression analyses, older age was associated with decreased odds of receiving ≥4 cycles of capecitabine (OR=0.25; 95% CI: 0.11–0.60; p =0.002). Among capecitabine users, 3-year OS was 46% and 78% for patients who received 1-3 and ≥4cycles of capecitabine, respectively (p&lt; 0.001). The 3-year estimate of BCSS was 43% and 85% respectively (p&lt; 0.001). After multivariable adjustment for comorbidity score, stage, and propensity score, receiving ≥4 cycles of capecitabine was associated with decreased risk of death (HR=0.29; 95%CI 0.13–0.63, p=0.002) and breast cancer-specific death (HR=0.15; 95%CI: 0.05–0.51, p=0.002) compared to receiving 1-3 cycles. Twenty-seven (28%) patients had ER/hospitalization during capecitabine treatment; median time from initial capecitabine claim to ER/hospitalization was 24 days (IQ 13-39). The median number of capecitabine cycles was 3 (IQR 2-5) and 5 (IQR 3-8) for those with and without ER/hospitalization (p=0.02). The most common diagnosis codes associated with ER/hospitalization included pleural effusion, GI symptoms, pneumonia, and acute kidney failure. A higher comorbidity score at diagnosis was associated with an increased risk of ER/hospitalization (HR=2.76; 95%CI 1.05-7.28, p=0.04).
Conclusion: We demonstrate an increasing trend in capecitabine utilization among elderly patients with early-stage TNBC. Although the limited sample size hindered a conclusive analysis, more cycles of capecitabine were associated with improved survival outcomes. Notably, a significant proportion of patients undergoing capecitabine treatment experienced ER/hospitalizations. These findings contribute valuable information on the risks and benefits of capecitabine treatment, aiding evidence-based decision-making to prevent serious complications.
Citation Format: Marija Sullivan, Xiudong Lei, Catalina Malinowski, Sharon Giordano, Marianna Chavez. Use of adjuvant Capecitabine after neoadjuvant chemotherapy: A Cohort Study among Elderly Patients with Early-Stage Triple-Negative Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-03-08.