This book is a critical appraisal of the data and evidence available in literature of the relative roles of the immune response to neoplastic cells. An attempt has been made to render a better understanding of the various modes of impact of the immune response against tumors in general, particularly gliomas in some of the chapters. Autoimmune response is one mode of reactivity to native component cells within the body. Neoplastic transformation, on the other hand, critically necessitated the absence of an effective immune response to the transformed tumor cells in order for the lesion to grow and metastasize. This book is aimed towards a wider readership, but its particularly for oncologists and the various clinical and academic professionals that care for patients with cancer. It is especially meant to provide a clear exposition of known facts regarding the genesis and further development of neoplasms. Examples of some of the commoner lesions are accounted for.