Abstract P5-14-12: Long-term outcome of HER2-normal early stage breast cancer (ESBC) patients (Pts) treated with docetaxel-cyclophosphamide (TC) chemotherapy (CTx): Mature results of a single-institution experience

Abstract

Abstract BACKGROUND Anthracycline(A)-containing regimens (AReg) became an established standard (neo)adj CTx for ESBC following fairly consistent demonstration of a modest superiority over older anti-metabolite/alkylating CTx. However, substantial translational data and a recently presented pooled analysis [Blum, 2016] suggest that this superiority could be largely driven by greater benefits in specific ESBC subgroups, i.e. HER2-altered BrCa (due to co-amplification of topoisomerase 2 and HER2), and triple-negative BrCa (TNBC). A are cardiotoxic (including late onset of cardiomyopathic congestive heart failure) and potentially leukaemogenic. In late 2006, following the results of the first USONC randomized clinical trial that showed superior outcomes of the non-AReg TC (docetaxel/cyclo­phosphamide) over AC, we established a routine, uniform policy of TC for all Pts receiving (neo)adj CTx for HER2-normal ESBC. We report the mature follow up of this single-institution unselected experience. METHODS We performed a retrospective outcome analysis of all Pts who received at least 1 cycle of (neo)adj TC (docetaxel 75 mg/m2 + cyclophosphamide 600 mg/m2 IV every 3 weeks) at our Department for HER2-normal ESBC and with at least 5 years of follow up (FU). Pts were identified by systematic analysis of the dataset of the Oncology Pharmacy Unit. Information on tumour characteristics [e.g. axillary lymph nodes (N) metastases, hormonal receptors (HR) and HER2 status] and Pts FU were retrieved and collected into an ad hoc designed database. Pts with node-positive (N+) ESBC received TC×6 cycles, and Pts with high-risk node-negative (N−) [e.g. primary tumour (T) >2 cm, or HRneg, or T >3 cm] ESBC received TC×4 cycles. Pts received adjuvant hormone therapy and radiotherapy as per standard of care. From 2008 on, many lower risk HR+/N− Pts were not given CTx due to OncotypeDx availability. RESULTS Between September 2006 and December 2015, 810 female HER2-normal ESBC Pts were treated with (neo)adj TC. In the final outcome analysis we included 464 Pts treated before June 2011 thus having a minimum FU of 5 years. Pts characteristics are: median age 53 yrs (range 30-77), N− 246 (53%), N+ 218 (47%), hormone receptors positive (HR+) 391 (84%), TNBC 73 (16%). The database was locked as of June 1st 2016. Median FU from first cycle of TC is 7.5 yrs (range 5.3-10). 63 BrCa-specific relapse events (defined as time to local, regional or distant recurrence, invasive contralateral breast cancer, excluding non-breast second primaries) have been observed, accounting for an overall Relapse-Free Survival (RFS) rate of 86.4%. 42 deaths have occurred, 36 (86%) due to BrCa, accounting for an Overall Survival (OS) rate of 91%. RFS and OS rates for the different Pts subgroups are reported in Table 1 Table 1 - Outcome parameters RFS (%)OS (%)All Pts8691HR+/N-9396HR+/N+8190TN/N-9191TN/N+5858 CONCLUSIONS These mature data with long FU suggest that the outcome for a large cohort of unselected Pts with HER2-normal HR+ ESBC (regardless of nodal status) and for TN/N− ESBrCa treated with nonAReg TC is excellent. However, N+TN ESBrCa in this setting remains a significant clinical challenge. Citation Format: Losurdo A, Gullo G, Buckley C, Lowry C, Ballot J, Silva N, Hammond L, Crown J. Long-term outcome of HER2-normal early stage breast cancer (ESBC) patients (Pts) treated with docetaxel-cyclophosphamide (TC) chemotherapy (CTx): Mature results of a single-institution experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-14-12.