background : central nervous system tumors account for 2%-5% of all malignancies in humans. these tumors account for 2% of all pediatric cancers. the worldwide incidence of primary central nervous system tumors is estimated at 3.9 (males) and 3.2 (females) per 100000 person-years. the incidence of brain tumor cases has been reported as 3.67% of all malignancies and 4% of all cancer mortalities ...