A24 - First line trastuzumab-based therapy in her2-positive metastatic breast cancer patients presenting with de novo or recurrent disease

Abstract

Background: Approximately 5-10% of breast cancer (BC) patients (pts) have metastases at the time of diagnosis (de novostage IV), suggesting distinct biological and clinical implications as compared to those relapsing after prior treatment for early stage BC (recurrent disease). We evaluated the patterns of care and clinical outcomes of HER2-positive metastatic breast cancer (MBC) pts receiving first line trastuzumab-based therapy, according to the type of metastatic presentation. Materials and methods: This is an ancillary study of a retrospective cohort study conducted in 14 Italian centers within the GIM (Gruppo Italiano Mammella) group. Consecutive pts undergoing first-line trastuzumab-based therapy were eligible for the study. Analyses were performed according to the type of presentation of metastatic disease (de novoor recurrent). Dichotomous clinical outcomes were analyzed using logistic regression and time-to-event outcomes using Cox proportional hazards models controlling for relevant demographic, clinicopathologic and therapy characteristics. All data were analyzed using Stata 12.3 (StataCorp LP). Results: A total of 416 MBC pts (median age, range 42–63 years) were included, 113 (27.2%) with de novo stage IV and 303 (72.8%) with recurrent disease: 64 (56.6%) and 186 pts (61.4) had hormone-receptor positive disease, respectively. Among pts with recurrent disease 101 (33.3%) received prior trastuzumab-based therapy in the (neo)adjuvant setting. Overall survival (OS) and progression-free survival (PFS) median follow-up were 2.59 years (1.56–4.41) and 1.11 years (0.63–2.17), respectively. In pts with de novo stage IV disease and in those with recurrent disease the following outcomes were observed, respectively: objective response rate (complete response + partial response), 163 pts (67.1%) vs 72 pts (72.0%) (adjusted OR = 0.90; 95% CI 0.34–2.38; p = .833); clinical benefit rate (complete response + partial response + stable disease), 76 pts (76.0%) vs 187 pts (77.0%) (adjusted OR = 1.21; 95% CI 0.40–3.64; p = .731); median PFS, 14.4 months vs 14.7 months (adjusted HR = 1.21; 95% CI 0.79–1.86;p = .380);median OS, 55.9 months vs 49.0 months (adjusted HR = 1.26; 95% CI 0.71–2.23; p = .439). Conclusions: The study shows that clinical outcomes of HER2-positive MBC pts with de novo stage IV disease do not differ significantly from those of pts with recurrent disease.