The role of chemotherapy in the treatment of patients with brain metastases from solid tumors

Brain metastases are the most frequent cancer in the central nervous system, being ten times more common than primary brain tumors. Patients generally have a poor outcome with a median survival of 4 months after diagnosis of the metastases. Therapeutic options include surgery, stereotactic, radiosurgery, whole-brain radiotherapy (WBRT), and chemotherapy. Patients with a limited number of brain metastases and well-controlled systemic cancer benefit from brain metastases-specific therapies, including surgery, radiosurgery, and conventional radiation. The role of chemotherapy for brain metastases remains limited. There is concern about drug delivery because of the blood-brain barrier. However, higher response rates are noted with initial therapies, suggesting that part of the poor response rate may be related to the late onset of brain metastases and the use of second- and third-line regimens. Recent studies have demonstrated objective responses with systemic therapy in a variety of cancer types, especially when combined with WBRT. Individual therapeutic strategies for central nervous system metastases must be chosen based on performance status, the extent of intracranial disease, and the chemosensitivity of the underlying tumor, as well as the control of the systemic cancer. In this article we review important prognostic factors and challenges in using chemotherapy. We specifically review recent advances in the treatment of brain metastases from breast and lung cancer as well as melanoma. Future treatment advances will require a multidisciplinary approach integrating surgical, radiation, and chemotherapeutic options to improve neurological function and quality of life, rather than just focusing on survival endpoints.