Refining the TCGA Framework: The Pivotal Role of Targeted Next-Generation Sequencing in Resolving Diagnostic Ambiguities in Endometrial Cancer—Systematic Review

The classification of endometrial cancer based on histological examination often fails to accurately predict treatment outcomes for patients. The Cancer Genome Atlas (TCGA) has proposed a new molecular model that more accurately identifies the tumour subtype, enabling more precise treatment. However, its implementation in daily practice remains a challenge. This systematic review assesses the key role of targeted next-generation sequencing (NGS) in refining the TCGA model and resolving these diagnostic ambiguities. A systematic review was conducted using the PubMed, Scopus, and Embase databases, focusing on studies published mainly between 2019 and 2025. Original studies and clinical guidelines concerning the evaluation of targeted NGS panels, surrogate markers, and the clinical significance of molecular subtypes in endometrial cancer were analysed. Based on the PRISMA guidelines, 11 relevant studies were used in the review. NGS is of key importance, particularly for the detection of POLE gene mutations that cannot be identified using traditional immunohistochemistry. The studies confirm that NGS accurately classifies tumours that exhibit more than one molecular feature. Although sequencing requires more time and resources, it provides a more objective and reproducible diagnostic model. Furthermore, NGS panels currently allow patients to be divided into four prognostic groups with a 100% survival rate in the POLE subtype. Across independently reported cohorts, concordance between NGS and IHC for MMR/p53 status ranged from roughly 65% to 98% depending on the platform and gene target, and NGS-based germline testing identified Lynch syndrome in 9–10% of patients screened; targeted panels also detected homologous-recombination-repair alterations (e.g., BRCA1/2, ATM, CHEK2) relevant to PARP-inhibitor eligibility. NGS combined with immunohistochemistry enables the most accurate diagnosis of patients with endometrial cancer. This combined approach reduces diagnostic errors and also provides the basis for decisions regarding personalised treatment. The introduction of targeted sequencing as a standard clinical tool allows for greater precision in tumour classification and improves the quality of patient care.