Uterine leiomyomas (ULM) and uterine leiomyosarcomas (ULMS) represent smooth muscle tumors with similar initial presentations but drastically different outcomes. This literature review analyzes the similarities and differences in their epigenetic profiles to identify diagnostic biomarkers and potential therapeutic targets that could improve clinical management. Both tumor types exhibit mostly distinct epigenetic signatures while sharing key pathway dysregulations. ULMS demonstrates global DNA hypomethylation, increased histone acetyltransferase activity, elevated Histone Deacetylase (HDAC) class I expression, and characteristic microRNA profiles. ULM displays focal methylation patterns and specific microRNA alterations that promote extracellular matrix accumulation. Despite these differences in epigenetic mechanisms, both tumors converge on dysregulation of signaling pathways including PI3K/AKT/mTOR, Wnt/β-catenin, and Transforming Growth Factor beta (TGF-β) signaling, suggesting common downstream effects from distinct epigenetic origins. Understanding the shared and distinct epigenetic landscape between ULM and ULMS will enhance our insights into tumor pathogenesis and may offer promising biomarkers and therapeutic targets.

Background: DNA damage response (DDR) pathway alterations contribute to genomic instability and malignant progression in several cancers. Methods: We retrospectively reviewed molecular profiles from 5309 sarcoma patient samples, including 746 from pediatric/adolescent and young adults (ped/AYA), encompassing 38 histologic subtypes. The gene expression profiles were further analyzed for immunotherapy-related biomarker associations, including analysis of the T cell-inflamed score. Results: Pathogenic/likely pathogenic DDR alterations were detected in 15.9% (N = 842) of samples overall and 9.25% (N = 69) of Ped/AYA tumors, with mutations occurring most frequently in ATRX (10.1%). Shorter overall survival was observed for patients with DDR-alterations compared to those with DDR-wildtype tumors (Hazard Ratio = 1.172, 95% CI: 1.068–1.287; p < 0.001). In many subtypes, DDR-mutated tumors were found to have increased rates of immune markers, including PD-L1+, dMMR/MSI-high, and TMB. Conclusions: Our study of somatic DDR-pathway mutations provides a better understanding of the molecular associations across sarcoma subtypes that may aid in developing future prognostic and therapeutic options for these rare cancers.