Chemotherapy and Future Developments

Abstract

The incidence of primary malignant brain tumors has been increasing over the past 30 years, and it is estimated that in the year 2010, approximately 22,020 cases were diagnosed in the USA alone, with 13,140 deaths [1, 2]. Gliomas account for 32% of all primary brain tumors, but within the malignant subset, they account for 80% of tumors. Histological classification of tumors of the nervous system was initiated by the WHO in 1979, as a means of predicting the biological behavior of a neoplasm, and thereby determining the choice of therapies. The 2016 World Health Organization Classification of Tumors of the Central Nervous System (CNS) is both a conceptual and practical advance over its 2007 predecessor (Table 4.1). For the first time, the WHO classification of CNS tumors uses molecular parameters in addition to histology to define many tumor entities, thus formulating a concept for how CNS tumor diagnoses should be structured in the molecular era. As such, the 2016 CNS WHO presents major restructuring of the diffuse gliomas, medulloblastomas, and other embryonal tumors, and incorporates new entities that are defined by both histology and molecular features, including glioblastoma, IDH-wild-type and glioblastoma, IDH-mutant; diffuse midline glioma, H3 K27 M-mutant; RELA fusion-positive ependymoma; medulloblastoma, WNT-activated and medulloblastoma, SHH-activated; and embryonal tumor with multilayered rosettes, C19MC-altered. The 2016 edition has added newly recognized neoplasms, and has deleted some entities, variants, and patterns that no longer have diagnostic and/or biological relevance. Other notable changes include the addition of brain invasion as a criterion for atypical meningioma and the introduction of a soft tissue-type grading system for the now combined entity of solitary fibrous tumor/hemangiopericytoma a departure from the manner by which other CNS tumors are graded. Overall, it is hoped that the 2016 CNS WHO will facilitate clinical, experimental, and epidemiological studies that will lead to improvements in the lives of patients with brain tumors [3].