2023 FIGO staging system for endometrial cancer: The evolution of the revolution

Embracing the complex and diverse nature of the heterogenous group of malignancies that are included under the umbrella of "endometrial cancer" (EC) to better align prognosis with treatment recommendations, requires a more comprehensive staging system. Our goal at the development of the new FIGO staging was to provide 1) high accuracy in the predictive prognosis for a patient with EC, which is the genuine purpose of a staging system, and 2) identification of distinct treatment relevant subgroups. Since the publication of the 2009 staging system by the International Federation of Gynecology and Obstetrics (FIGO) 14 years ago (1, 2), our understanding of the biology and natural history of EC has undergone a radical transformation. The TGCA results in 2013 (3), and the many validation reports published since then (4-9), have taught us that "EC" is composed of at least four distinct molecularly defined diseases. Strong histopathologic markers reflecting tumor biology such as lymph vascular space invasion (LVSI) were identified. Importantly, anatomical borders were shown to lose their prognostic relevance for EC patients in the presence of dominant tumor biology-markers such as molecular subtypes/LVSI (10, 11). This emphasizes the integration of these novel markers into a prognostic staging system that aims to be relevant to patients. The 2023 FIGO staging system for EC harmonizes and integrates old and new knowledge on anatomic, histopathologic, and molecular features (12). It requires a change in our perception of a staging system, from a traditional purely anatomical borders-based system to an integrated staging system integrating anatomical borders and tumor biology as pivotal prognostic factors for EC patients while providing important information for treatment decision making. Therefore, the 2023 FIGO staging system demonstrates the logical next step in the evolution of the revolution in a patient-centric staging approach. Below, we elucidate the rationale for the FIGO 2023 endometrial cancer staging system.