Thymoma (THYM)

Overview

Thymoma encompasses WHO types A, AB, B1, B2, and B3 thymic epithelial tumors; in OncoTree THYM is a child of TET under THYMUS. Indolent types A/AB are defined by a recurrent GTF2I hotspot mutation (p.Leu404His) present in ~78% of combined type A/AB cases, distinguishing them molecularly from the more aggressive B-type thymomas and thymic carcinomas.

Cohorts in the corpus

Recurrent alterations

  • GTF2I p.Leu404His (chr7:74146970 T>A) in 82% of type A, 74% of type AB, 78% combined A/AB thymomas (n=270 TETs total); associated with 96% 10-year disease-related survival vs 70% for GTF2I wild-type (P<0.001); GTF2I mutation was enriched in early-stage (I–II, 57%) vs advanced (III–IV, 19%) disease PMID:24974848.
  • Mutation burden is significantly lower in thymomas than thymic carcinomas (mean 18.4 vs 43.5 coding mutations per sample; P=0.001) PMID:24974848.
  • MC3 pan-cancer mutation-calling project (10,510 TCGA pairs) included THYM; THYM showed large sample-to-sample variability in mutations per sample attributable to low tumor purity (median ABSOLUTE purity 39.0%) PMID:29596782
  • Pan-cancer fusion study (9,624 TCGA samples) found THYM had a median of 0 fusions/sample (low-fusion cancer type) but the highest mean predicted fusion-derived neoantigens (2.88 per fusion among cancer types) PMID:29617662
  • Pan-cancer aneuploidy study found THYM has one of the lowest mean aneuploidy scores (3.8), consistent with being a near-diploid cancer type; THYM was included in the pan-cancer cohort of 10,522 TCGA tumors PMID:29622463

Subtypes

  • Type A/AB: most indolent; GTF2I-mutation dominant; almost no copy-number aberrations.
  • Type B1/B2/B3: intermediate; GTF2I prevalence decreases with increasing aggressiveness.

Therapeutic landscape

  • No drug pages currently linked for THYM in this corpus. GTF2I mutation status is proposed as a complement to WHO histological classification for prognostic stratification.

Sources

This page was processed by entity-page-writer on 2026-05-11. - PMID:29596782

This page was processed by wiki-cli on 2026-05-15. - PMID:29617662

This page was processed by wiki-cli on 2026-05-15. - PMID:29622463

This page was processed by wiki-cli on 2026-05-15.