This is the new classification of brain tumors. It is very confusing and very different. However, it is way more specific. Previously, they changed Glioblastoma Multiforme into 2 groups: Glioblastoma, IDH mutant and Glioblastoma, IDH Wildtype. Now they changed it so that the only tumor that can be called a Glioblastoma has to be IDH wild type. If the tumor has an IDH mutation, it is not longer considered a Glioblastoma (or a Glioblastoma, IDH Mutant - which is now removed from the classification scheme.) This makes sense because the tumors act very differently and you really can not group the two together in a clinical trial and expect it to make any sense at all. In general, patients with what used to be called Glioblastoma multiforme with an IDH mutation live twice as long as those without the mutation. (31 months with IDH mutations, and 15 months without). They also changed from using the roman numeral system to arabic numbers. These are much easier to read and less prone to error! So a Glioblastoma is now consider a grade 4 instead of IV. And it has to have wildtype IDH.