Improved Survival of HER2-Positive Metastatic Breast Cancer in Routine Care

Purpose: Targeted therapy directed against HER2 has improved the outcome of patients with HER2-positive metastatic breast cancer in prospective clinical trials. No data are available how anti-HER2-therapy has influenced survival of unselected patients with HER2-positive metastatic breast cancer who receive treatment in routine care. Methods: Data of 118 subsequent patients with HER2-positive metastatic breast cancer who were treated in a community-based oncology group practice between 1995 and 2010 were analyzed retrospectively. Results: Median age at initial diagnosis of metastasis was 58 years (33-92). Twenty-two percent were metastasized at diagnosis of breast cancer, seventy-eight percent developed metastases in the course of the disease. Distribution of metastatic sites at initial diagnosis of metastasis was: 23% bone, 58% visceral, 5% CNS, 10% lymph nodes, 4% other. Hormone receptor was positive in 68% and negative in 31%. Palliative treatment consisted of antihormonal therapy in 56%, chemotherapy in 90% and radiotherapy in 50%. Seventy-five percent received anti-HER2-therapy consisting of trastuzumab in 80% and lapatinib in 1%, 19% received trastuzumab + lapatinib sequentially. Twenty-five percent received no anti-HER2-therapy. Median overall survival since initial diagnosis of metastasis was 34 months (0-277+). Conclusion: It could be shown that, compared to historical controls, targeted therapy against HER2 prolongs overall survival of patients with HER2-positive metastatic breast cancer who receive treatment in routine care.