The New Era of Molecular Classification (TCGA Framework)
The traditional histopathological method of grading tumors is now being augmented—and in some cases replaced—by the The Cancer Genome Atlas (TCGA) molecular classification.
This framework divides endometrial cancer into four distinct molecular subgroups, which provide far more accurate prognostic data than traditional staging alone:
POLE-ultramutated: Characterized by mutations in the $POLE$ exonuclease domain. These patients have an exceptionally high mutational burden but, paradoxically, the best clinical outcomes.
MSI-H (Microsatellite Instability-High): These tumors have a deficiency in the Mismatch Repair (MMR) system. They are highly immunogenic and are primary candidates for immunotherapy.
Copy-number low (NSMP): These are typically low-grade endometrioid cancers with few genetic alterations and a moderate prognosis.
Copy-number high (Serous-like): These tumors exhibit extreme genomic instability and carry the poorest prognosis, regardless of their stage at diagnosis.
Integrating this data into routine practice allows oncologists to de-escalate treatment for $POLE$ patients (sparing them from toxic chemotherapy) while intensifying treatment for "Serous-like" patients who might otherwise be undertreated.