**2. Epidemiology**

The incidence can change by age; in adults, for example, gliomas are the most frequent primary central nervous system tumors recurring in 70% of the patients. The average age of patients with GBM primary is 62 years, while for secondary GBM patients, it is approximately 45 years. The ethnicity and geographical localization are also of great importance in their epidemiology [1]. These tumors represent about 31% of newly diagnosed tumors in the United States and 81% of malignant tumors of the brain. The incidence of brain cancer in Europe is of 5.5/100,000 individuals, and the minor incidence is in sub‐Saharan Africa with 0.8/100,000 individuals [2]. High‐grade gliomas, anaplastic astrocytoma (AA) and GBM, have an incidence of 6.03/100,000 [3,4]. It has been shown that the incidence of GBM with respect to gender and ethnicity was different. The white people had the highest incidence of 2.5/100,000, Latin white people 1.8/100,000, and black people 1.5/100,000 [5].
