Lower-Grade Glioma / LGG (TCGA)

Overview

LGG is the TCGA cohort identifier for lower-grade glioma (WHO grade II–III). The closest OncoTree equivalent is LGGNOS (Lower Grade Glioma, NOS) or DIFG (Diffuse Glioma). LGG is defined primarily by IDH mutation status and 1p/19q co-deletion, which separates oligodendroglioma from astrocytoma subtypes.

Cohorts in the corpus

  • TCGA LGG cohort: included as one of 33 cancer types in the pan-cancer fusion landscape study and the pan-cancer aneuploidy study; subset of the PanCancer Atlas.

Recurrent alterations

  • Pan-cancer fusion study (9,624 TCGA samples) found LGG has a median of 0 fusions per sample (low-fusion cancer type); IDH-mutant LGG clusters separately from IDH-wildtype GBM by arm-level aneuploidy pattern PMID:29617662.
  • Pan-cancer aneuploidy study found IDH1 mutation defines the LGG subgroup that clusters separately from GBM by aneuploidy pattern, characterized by 1p loss and 19q gain; LGG clusters in the neural-lineage arm-level group with GBM and melanoma PMID:29622463.

Subtypes

  • IDH-mutant, 1p/19q co-deleted: oligodendroglioma; characterized by low arm-level aneuploidy except 1p/19q.
  • IDH-mutant, 1p/19q intact: astrocytoma; typically lower aneuploidy than GBM.
  • IDH-wildtype LGG: behaviorally similar to GBM; not expected to be common in the TCGA LGG cohort by design.
  • The 1p/19q co-deletion in LGG (Cairncross et al., 2013) is a precedent for arm-level alterations being therapeutically relevant PMID:29622463.

Therapeutic landscape

No drug-specific findings for LGG reported in the current corpus beyond IDH-inhibitor relevance.

Sources

  • PMID:29617662 — Pan-cancer fusion landscape (Gao et al., 2018)
  • PMID:29622463 — Pan-cancer aneuploidy landscape (Taylor et al., 2018)

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