I. Introduction
A brain tumor is an abnormal mass of tissue in which cells grow and multiply uncontrollably, seemingly unchecked by the mechanisms that control normal cells. In recent years, there has been rapid increase in the number of patients suffering from brain tumor. In spite of aggressive conventional and advanced treatments, the prognosis remains uniformly fatal. The reason is not only the rapid tumor growth but especially the fact that, long before the neoplasm can be diagnosed; it has already grossly invaded the surrounding brain parenchyma, rendering surgical removal virtually ineffective [1].