Fig. 2
Simplified diagram illustrating the adult glioma classification procedures based on the (a) WHO-2016 and (b) WHO-2021 guidelines, the fundamental theory of the proposed Method-2016 and Method-2021, respectively. White rounded boxes represent the simplified glioma types: Astro (astrocytoma), Oligo (oligodendroglioma) and GBM (glioblastoma). In blue, the IDH mutation status can be mutant (IDHmut) or wildtype (IDHwt). In the scheme, “Others” refer to IDHwt patients who would require further evaluation to be completely classified. (a) TCGA glioma samples came histologically classified as Astro, Oligo, Mixed glioma (“Mix”) or GBM. Following the WHO-2016 guidelines, Method-2016 proposes samples to be further categorised according to molecular features provided by Ceccarelli et al.6. LGG samples with IDH mutation are classified as Astro in the absence of 1p/19q codeletion, or classified as Oligo in the presence of 1p/19q codeletion, while LGG samples without IDH mutation (wildtype: WT) are classified as other glioma types (“Others” in the scheme). GBM samples can be further categorised, according to their IDH mutation status, as either GBM IDHwt or GBM IDHmut. (b) Per WHO-2021 guidelines, Method-2021 proposes initial sample classification based on molecular profiles. IDH-mutant samples can be labelled as Astro or Oligo based on the absence or presence of 1p/19q codeletion, respectively. GBM IDHwt samples that exhibit particular histologic/genetic features are classified as GBM, otherwise considered as other glioma types (“Others” in the scheme). Abbreviations: Astro, Astrocytoma; EGFR, epidermal growth factor receptor; GBM, glioblastoma; IDH, isocitrate dehydrogenase; Mix, Mixed-glioma (i.e. oligoastrocytoma); mut, mutant; Oligo, oligodendroglioma; TERT, Telomerase reverse transcriptase; WHO, World Health Organization; wt/WT, wildtype; +7/10-, combined gain of entire chromosome 7 and loss of entire chromosome 10.
