Trastuzumab in advanced breast cancer – a decade of experience in Germany

BACKGROUND: Trastuzumab was registered in 2000 for the treatment of metastatic breast cancer, both as monotherapy and combination therapy with paclitaxel. In this prospective, non-interventional observation study, the 10-year experience with trastuzumab in the routine management of HER2-positive breast cancer was reviewed. METHODS: Between 2000 and 2010, 1843 evaluable patients with advanced HER2-positive breast cancer were recruited in 223 institutions across Germany. Patients were prospectively monitored for about one year. Additional information on long-term outcomes, progression-free survival (PFS), and overall survival (OS) were retrieved at several follow-up points. There were no restrictions with respect to diagnostic or therapeutic procedures. Patients were stratified into three cohorts depending on the treatment regimen, i.e. trastuzumab monotherapy (n =228, 12%), trastuzumab combined with chemotherapy (n =1346, 73%), or trastuzumab combined with endocrine therapy (n =269, 15%). RESULTS: Median age was 59.5 years with a proportion of 28% being older than 65 years. Over a maximum follow-up period of more than 10 years, 1538 PFS events were documented in 83% of patients, resulting in an estimated median PFS of 11.8 months. Median OS, based on recorded death in 64% of patients, amounted to 34.4 months, with 48% (95% confidence intervals 45 – 50%) still alive after three years. The subgroup selected for a treatment combination with endocrine drugs only had distinctly longer PFS and OS than the other two groups, achieving medians of 23.3 months and 56.3 months, respectively. Median PFS and OS in elderly patients over 65 years of age was 11.4 months and 28.3 months, respectively. Adverse reactions, including cardiac toxicity, of severity grade 3 or 4 were rare. CONCLUSIONS: The superior outcome of treatment strategies including trastuzumab in HER2 overexpressing breast cancer, proven in pivotal studies, was confirmed in the management of advanced breast cancer in Germany in the routine setting. Our data suggest a comparable clinical benefit of treatment with trastuzumab in elderly patients (>65 years), who are typically under-represented in randomized clinical studies.