100P - Impact of perioperative fluoropyrimidines on the efficacy of capecitabine in patients with advanced breast cancer: A retrospective study

Abstract

Background: It is unclear whether perioperative fluoropyrimidine (FP) use impacts the efficacy of capecitabine in advanced breast cancer treatment. Methods: Medical records of patients with advanced breast cancer who received capecitabine between 2008 and 2016 at National Cancer Center Hospital (Tokyo, Japan) were reviewed. Progression-free survival (PFS), overall survival (OS), tumor response, and adverse events (AEs) were compared between a FP group (prior perioperative FP use) and a non-FP group (no prior FP use). To evaluate the effect of prior perioperative FP use on survival outcomes, hazard ratios (HRs) for PFS and OS were estimated for the FP group compared with the non-FP group. Results: A total of 289 patients (FP group: n = 106; non-FP group: n = 183) were analyzed. Patient characteristics were similar between the two groups. The median recurrence-free interval (RFI) was 3.94 (range: 0.27-20.11) years in the FP group and 4.24 (range: 0.27-27.07) years in the non-FP group (p = 0.402). The FP group had poorer PFS than the non-FP group (univariate HR: 1.33; 95% confidence interval [CI]: 1.03-1.72, p = 0.028; multivariate HR: 1.33; 95% CI: 1.02-1.73; p = 0.034). However, OS was similar between the groups (univariate HR: 1.16; 95% CI: 0.84-1.62; p = 0.368; multivariate HR: 1.06; 95% CI: 0.74-1.51; p = 0.755). Multivariate HRs for PFS for the FP group with short RFI and long RFI (cutoff: RFI=4 years) separately were 1.56 (95% CI: 1.06-2.28; p = 0.025) and 1.20 (95% CI: 0.84-1.70; p = 0.326), respectively. With different cutoffs (RFI=3, 4, and 5 years), the ranges of adjusted HRs for PFS were 1.32-1.67 with short RFI, and 1.00-1.25 with long RFI. A trend for larger HR for the FP group with short RFI than with long RFI was also seen for OS with different cutoffs of RFI. The response rate (FP group vs. non-FP group) was 21.0% vs. 14.8% (p = 0.306), and the disease control rate was 59.9% vs. 54.5% (p = 0.422). There was no significant difference in AEs between the two groups. Conclusions: Capecitabine can be used for patients with advanced breast cancer with FP use history, as OS does not correlate with prior FP use. For patients with FP use history, RFI may be a relevant factor for treatment selection. Legal entity responsible for the study: National Cancer Center Hospital Funding: None Disclosure: All authors have declared no conflicts of interest.