Efficacy of different dosing schedules of capecitabine for metastatic breast cancer: a single-institution experience

Use of adjuvant capecitabine in older patients with early-stage triple-negative breast cancer

PURPOSE

Patients with triple-negative breast cancer (TNBC) who have residual disease after neoadjuvant chemotherapy (NACT) benefit from adjuvant capecitabine. Older patients are not always treated according to guidelines, likely due to concerns regarding tolerance. We examined the use of adjuvant capecitabine, its association with outcomes, and subsequent emergency room visits (ER) and hospitalizations (HSP) among older patients with early-stage TNBC.

METHODS

Retrospective, observational study using data in the SEER-Medicare database. Older patients (≥ 66 years) with early-stage TNBC, diagnosed in 2010-2019, who received NACT, underwent surgery, and were prescribed adjuvant capecitabine were included. We analyzed capecitabine use, its association with overall survival and breast-cancer specific survival, and time to first ER/HSP. Logistic regression, Kaplan-Meier estimates, and Cox regression models with propensity score adjustments were used.

RESULTS

239 of 1,799 older patients with TNBC received adjuvant capecitabine. Capecitabine use increased from 1.3% in 2010 to 29.6% in 2019. Older age, ≥ 71 years, (OR = 0.54, 95%CI 0.32-0.92) and ≥ 2 comorbidities (OR = 0.42, 95%CI 0.2-0.9) were associated with decreased odds of receiving ≥ 6 cycles of capecitabine. Increasing number of cycles of capecitabine was associated with decreased risks of death (HR = 0.74, 95%CI 0.66-0.83) and breast cancer-specific death (HR = 0.73, 95%CI 0.61-0.89). 55 patients (23%) treated with capecitabine experienced ER/HSP.

CONCLUSION

In recent years, adjuvant capecitabine is increasingly used for patients with early-stage TNBC. Patients with older age and more comorbidities received fewer cycles of capecitabine. While one-fourth of patients had ER/HSP, receipt of more cycles was associated with better survival.

Retrospective evaluation of adjuvant capecitabine dosing patterns in triple negative breast cancer

BACKGROUND

The CREATE-X trial demonstrated that adjuvant capecitabine was effective in prolonging survival in high-risk triple-negative breast cancer (TNBC) patients. However, the recommended dose is generally not well tolerated by the US population. The goal of this study is to analyze dosing patterns in an ethnically diverse cohort to better characterize tolerability and inform future dosing guidelines.

METHODS

In our single-center retrospective study, we evaluated safety and tolerability in TNBC patients undergoing adjuvant capecitabine treatment. The primary endpoint, relative dose intensity (RDI) across eight cycles, was examined alongside subgroup analyses based on age, race, BMI, and initial dose. Secondary endpoints include capecitabine-related side effects and survival.

RESULTS

67 patients who completed adjuvant capecitabine at University of Chicago Medicine (UCM) between January 2017 and November 2022 were eligible. The mean RDI across eight cycles of treatment was 60.2% (95% CI: 0.554-0.650). When compared to the CREATE-X trial, the RDI in our population was significantly lower (0.602 vs. 0.787, p < 0.001). There was no statistically significant difference in average RDI across eight cycles for patients stratified by age, BMI, race, or initial starting dose. The most frequently reported adverse events were hand-foot syndrome (73%), diarrhea (27%), and fatigue (22%), consistent with prior studies.

CONCLUSIONS

Our data demonstrates that a significant portion of patients have a lower tolerated dose of capecitabine in comparison to the recommended adjuvant dose. Acknowledging the limitations of our single-center analysis, RDI was not significantly affected by age, race, BMI, or initial starting dose.