[The biology of human brain tumors]

For the most part, the prediction of prognosis and the design of treatment modalities for patients with brain tumors are judged equivocally by histopathological examination which is empirical and often subjective. While we incompletely understand tumor malignancy, some of the biological features of malignancy such as 1) phenotypic expression, 2) cellular invasiveness, and 3) the rapidity of proliferation should be independently determined. We need some objective methods to analyze these factors quantitatively in order to predict prognosis with certainty and to design tailored treatment modalities. As the brain is encased within the skull, the space available for a tumor to grow before it reaches a size fatal to the patient is severely limited. Thus, prognosis and/or survival of a patient with a brain tumor should be closely related to size and growth rate of an individual tumor and the quantitation of growth potential of an individual brain tumor is extremely important. The development of a monoclonal antibody against bromodeoxyuridine, a thymidine analogue, has made it possible to rapidly estimate proliferative potential of human brain tumors in situ by means of immunohistochemistry. The author reviewed current studies on growth characteristics of various brain tumors and discussed the usefulness of such studies.