Abstract P1-13-02: Real world outcomes of adjuvant FECD, ddACT and ACT for the treatment of early stage breast cancer - A multicenter retrospective analysis

Background: Adjuvant chemotherapy combining anthracyclines and taxanes for early stage breast cancer (ESBC) have demonstrated disease-free survival (DFS) and overall survival (OS) benefits. Among the 3rd generation regimens, 2 options have been favoured: FEC-Docetaxel (FECD) and AC-Paclitaxel (ACT). ACT may be delivered with dose-dense (ddACT) or weekly taxane scheduling (ddACWT), compared to traditional every 3-weekly (q3ACT) scheduling. Despite literature supporting both FECD and (dd)ACT regimens in the management of ESBC, no direct prospective trial has evaluated their comparative effectiveness. Methods: A retrospective review of the BC Cancer Breast Cancer Outcomes Unit (BCOU) and the Alberta Health Services (AHS) databases was performed to identify patients with HER2 negative, stage 1-3 ESBC, who received adjuvant chemotherapy between 2007-2014. The primary endpoint was OS and the secondary endpoint was RFS, defined as freedom from local (invasive), regional or distant recurrence or breast cancer death. Outcome comparisons were made between FECD, ddACT/ddACWT and q3ACT using the Kaplan Meier method. Treatment arms were compared using a log-rank test for univariate analysis. A multivariate analysis was also conducted for OS comprising age, stage, grade, receptor status and type of chemotherapy received (FECD vs combined ACT group). Results: A total of 4047 patients met inclusion criteria, including 2685 FECD, 1259 ddACT and 103 ACT. Median age was 53 (24-77) in the FECD group vs 52 (26-68) in the ddACT/ddACWT group and 58 (43-78) in the q3ACT group. The majority had stage 2 disease, 51.3%, 53.5% and 50.5% in the FECD, ddACT/ddACWT and q3ACT groups, respectively. Most were HR+, 84.5% in the FECD group vs 66.9% in both the ddACT/ddACWT and q3ACT groups. In the FECD group, 42.8% had a grade 2 tumour and 48.2% a grade 3 tumour vs 35.4% and 56.4% in the ddACT/ddACWT group and 35.0% and 58.3% in the q3ACT group. Lymphovascular invasion (LVI) was present in 40.7% of patients who received FECD vs 39.7% for ddACT/ddACWT and 26.2% for ACT. 5-year OS, for the FECD group was 90.3% (95%CI 89.1,91.4) vs 87.0% (95%CI 84.3,89.2) for the ddACT/ddACWT and 84.9% (95%CI 75.5,90.8) for the q3ACT groups, p=0.0907. 5-year RFS was 85.5% (95%CI 84.0-86.8) with FECD vs 84.4% (95% 81.9,86.6) for ddACT/ddACWT and 87.7% (95%CI 79.2,92.8) with q3ACT,p=0.4200. In multivariate analysis: age, stage and grade were significantly associated with OS whereas type of chemotherapy received (FECD vs ACT) was not (p=0.165). Finally, OS rates were compared across provinces and no significant differences were identified, 87.0% vs 88.0% (p=0.6294). Subgroup analyses by receptor type, comparing HR+ and TNBC are ongoing. Conclusions: The use of FECD as compared to ACT based chemotherapy did not reveal significant differences in OS or RFS in this population-based study. Further, chemotherapy regimen was not associated with differences in overall survival, as compared to other well recognized prognostic factors. While the results were obtained from a retrospective analysis, conclusive prospective data is lacking. These results may therefore reassure physicians and patients alike on a comparable efficacy of these regimens in a real-life setting. Citation Format: LeVasseur N, Veitch Z, Diocee RM, Gondara L, Cheung W, Khan O, Cossetti R, Gelmon KA, King K, Lupichuk S, Chia SK, Tang P, Simmons C. Real world outcomes of adjuvant FECD, ddACT and ACT for the treatment of early stage breast cancer - A multicenter retrospective analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-13-02.