Unsolved Issues in the Integrated Histo-Molecular Classification of Endometrial Carcinoma and Therapeutic Implications

Simple Summary In the past few years, the endometrial cancer field has been revolutionized, following the integration of molecular classification into clinical practice. Endometrial carcinoma is currently molecularly categorized into four main subgroups: POLE-mutated, mismatch repair-deficient, p53-mutated, and no specific molecular profile. The POLE-mutated subgroup is characterized by an excellent prognosis notwithstanding bad conventional prognostic factors, including high-grade and TP53 mutations. On the other hand, the p53-mutated subgroup demonstrates the worst outcome. However, the remaining subgroups are more prevalent and display variable clinical outcomes. In this review, we describe the evolution of the endometrial carcinoma classification, its strengths and limitations, clinical implications, and foreseen perspectives.Abstract Endometrial carcinoma (EC) is the most frequent gynecological cancer, with an increasing incidence and mortality in recent times. The last decade has represented a true revolution with the development of the integrated histo-molecular classification of EC, which allows for the stratification of patients with morphologically indistinguishable disease into groups with different prognoses. Particularly, the POLE-mutated subgroup exhibits outstanding survival. Nevertheless, the indiscriminate application of molecular classification appears premature. Its prognostic significance has been proven mainly in endometrioid EC, the most common histotype, but it has yet to be convincingly confirmed in the other minor histotypes, which indeed account for a relevant proportion of EC mortality. Moreover, its daily use both requires a mindful pathologist who is able to correctly evaluate and unambiguously report immunohistochemical staining used as a surrogated diagnostic tool and is hampered by the unavailability of POLE mutation analysis. Further molecular characterization of ECs is needed to allow for the identification of better-tailored therapies in different settings, as well as the safe avoidance of surgery for fertility preservation. Hopefully, the numerous ongoing clinical trials in the adjuvant and metastatic settings of EC will likely produce evidence to refine the histo-molecular classification and therapeutic guidelines. Our review aims to retrace the origin and evolution of the molecular classification for EC, reveal its strengths and limitations, show clinical relevance, and uncover the desired future developments.