Diffuse infiltrative gliomas are by far the most common primary brain tumors in adults, esp. its most malignant form, glioblastoma multiforme (Glioblastoma) 1).

Diffuse gliomas are the second most common central nervous system tumors, behind meningiomas, and account for roughly 80% of primary malignant brain tumors 2) 3) 4).

1)
CBTRUS (2006) CBTRUS statistical report. Primary brain tumors in the United States, 1998–2002. Central Brain Tumor Registry of the United States. http://www.cbtrus.org
2)
Bondy ML, Scheurer ME, Malmer B, et al. Brain tumor epidemiology: consensus from the brain tumor epidemiology consortium (BTEC). Cancer 2008;113:1953–68
3)
Jansen M, Yip S, Louis DN. Molecular pathology in adult gliomas: diagnostic, prognostic and predictive markers. Lancet Neurol 2010;9:717–26
4)
Theeler BJ, Yung WK, Fuller GN, et al. Moving toward molecular classification of diffuse gliomas in adults. Neurology 2012;79:1917–26