Tumor hormone/HER2 receptor status and pharmacologic treatment of metastatic breast cancer in Western Europe

Introduction: Tumor hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) expression are important factors influencing treatment response and selection in patients with metastatic breast cancer (mBC). Using the LifeLink Oncology Analyzer Database, we classified mBC patients by combined HR and HER2 status, and evaluated the use of pharmacological treatment modalities both overall and within these subtypes in Western Europe. Patients and methods: The study population included 4670 women with mBC from five Western European countries (France, Germany, Italy, Spain, UK). The most recent treatment administered (use of chemotherapy, endocrine therapy, HER2-targeted therapy, or others) and tumor marker (HR and HER2) status were captured. The results were summarized descriptively by combined tumor receptor status, current therapy type at the time of the survey, and age. Results: Combined tumor receptor status and the most recent treatment for mBC were known for 4070 and 4060 women, respectively. The proportion of patients with each subtype ranged from 12.6-53.5% of the overall population (HR-/HER2+ least common and HR+/HER2- most common). Overall, chemotherapy was the most frequently reported treatment used followed by endocrine therapy and HER2-targeted therapy (59%, 33% and 15% of patients, respectively). Patients aged <= 55 years were more likely to receive chemotherapy and less likely to receive endocrine treatment compared with patients aged >55. Patterns of treatment also differed by combined tumor receptor status and age although chemotherapy was consistently the mainstay of treatment. These results should be reviewed in light of the study limitations, including the cross-sectional nature of data, the heterogeneity of our mBC population (newly metastasized vs. extensively treated), and the variations in receptor status evaluation among participating centers. Conclusions: Our analysis highlights the heterogeneity of the mBC population in Europe and illustrates that treatment modalities differed by age and by combined HR/HER2 receptor status.