Survival Data of Patients with Anthracycline- or Taxane-Pretreated or Resistant Metastatic Breast Cancer

Metastatic breast cancer is considered incurable. Despite effective response rates achieved with anthracycline or taxane anticancer drugs, cancers in approximately one third of patients fail to respond to first-line treatment with these agents. Patients who do respond show disease progression after a median of approximately 7-8 months. As a consequence, the development of new salvage treatments and strategies for metastatic breast cancer continues to be a high priority. However, few randomized controlled trials have been conducted in patients in whom previous treatment with anthracyclines and taxanes fails. Among those trials that have, few demonstrated an improvement in overall survival. Overall survival is considered the gold standard for evaluating the benefits of experimental cancer therapies. In addition, many investigators use progression-free survival or time to progression. Survival outcomes from large trials of newer combinations, such as ixabepilone plus capecitabine and gemcitabine plus vinorelbine, are encouraging. They have shown significant benefits in terms of progression-free survival, and they have revealed demonstrable benefits for several hard-to-treat subgroups of patients with metastatic breast cancer. Addition of the targeted agents trastuzumab, bevacizumab, and lapatinib to chemotherapy has produced significant benefits in time to progression and progression-free survival. Ongoing research should help in determining which patients are likely to benefit from such agents when first- or second-line therapy fails and in ascertaining whether this therapy can be optimized to maximize therapeutic potential and minimize unnecessary toxicity.