This volume covers what is known regarding the natural history, basic biology, and clinical aspects, including imaging and treatment, of CNS metastasis. Three chapters cover the biology of the brain and brain metastases: molecular biology, includes what is known about specific genes/proteins involved in the process of metastasis and model systems to study brain metastasis; brain microenvironment, focuses on the resident cells of the microenvironment and their role in CNS metastasis; and the blood-brain barrier, includes a discussion of permeability with respect to brain metastases. A discussion of experimental imaging covers both the biology of brain metastasis from an imaging perspective and the use of imaging techniques to study brain metastases. The three clinical chapters discuss treatment options of surgery, chemotherapy, and radiation. The potential for novel targeted therapies is also addressed. Because of the uniqueness of the disease, leptomeningeal metastasis is discussed separately. The last chapter is devoted to quality of life issues associated with CNS metastasis.