Low grade gliomas subtype analysis. Low grade gliomas subtype analysis

Low grade gliomas (LGG; WHO grade 2 astrocytomas, oligodendrogliomas and oligoastrocytomas) account for about 25% of diffuse gliomas. Most occur in young adults between the ages of 30 and 45 years, and are usually only diagnosed after a seizure. In general, they can be characterised by a long period of continuous slow growth, followed by malignant transformation that will be the cause of death up to 25 years after onset. However, there is a significant number of patients for whom malignant progression is more rapid, with mortality observed within 5 years. This suggests that, as with other tumour types, there may be different subtypes of LGG with specific prognosis. It follows that being able to identify these subtypes may permit better patient stratification and aid targeted treatments. Until recently, our understanding of the variables involved in patient prognosis included the type of tumour – oligodendroglial tumours indicate better prognosis than oligoastrocytic or astrocytic – and presence of the 1p-19q co-deletion. In addition, the recent discovery of mutations in IDH1&2 in the majority of LGGs provided another means of stratifying patients, while offering an important insight into their biology. However, we still understand very little of the biology behind the genesis and progression of the 70-80% of LGG that bear IDH1&2 mutations, let alone the remaining IDH wild-type tumours.