Recent perspectives in brain tumor biology and treatment.

Tumors are composed of tumor cells, normal host cells, and an ECM. Tumor growth depends on the balance between tumor cell proliferation and tumor cell loss and is significantly influenced by normal vascular, immune, and glial cells of the host. Furthermore, tumor size and growth regulation are probably influenced by components of the ECM and by edema within and surrounding the tumor. To increase the therapeutic value of treatment regimens, investigators must study normal tissues and attempt to identify tumor-specific vulnerabilities and ways to inhibit toxicity to the host. We are entering an era of increased awareness of the complexities of tumor biology. Although our knowledge of tumor cell biology has had only a limited impact on the treatment for brain tumors, rationally developed approaches based upon new knowledge are bound to result in more effective treatment and improved prognosis for patients with brain tumors.