Introduction/Background*Endometrial cancer (EC) is the most common gynaecological malignancy in the USA, and mortality from advanced/metastatic EC (AEC) is increasing. EC constitutes a heterogeneous group of diseases with distinct histological subtypes. We characterized the prognosis in routine clinical practice of women with uterine serous carcinoma (USC), endometrioid carcinoma, clear-cell carcinoma (CCC), carcinosarcoma, and EC not otherwise specified.

Methodology This retrospective study utilized electronic health records from the US Flatiron database, comprising structured and unstructured data from community and academic centres. Women aged ≥18 years diagnosed with AEC (initial diagnosis: stage III/IV, or early stage with subsequent locoregional/distal recurrence) between 1 January 2013 and 30 September 2020, inclusive, were eligible provided they received platinum-based chemotherapy at any time following diagnosis and had ≥2 clinical visits. Patients were followed up from initiation of systemic treatment for recurrent/metastatic disease after advanced diagnosis until 31 March 2021, last available follow-up, or death (whichever occurred first). Overall survival (OS) and time to first subsequent therapy or death (TFST) were estimated with Kaplan-Meier methodology.

Result(s)*Overall, 2202 women with AEC were included; most (82.7%) were treated in a community setting and presented with stage III/IV disease at initial diagnosis (74.0%; table 1). Compared with other subtypes, a higher proportion (26.3%) of women with USC were Black/African American. Thirty-three (1.5%) patients did not have recorded therapy following AEC diagnosis. The most common first systemic treatments for recurrent/metastatic disease were platinum-based combination chemotherapy (82.0%), platinum-based single-agent chemotherapy (7.9%), and platinum-based chemotherapy plus HER2-targeted therapy (2.9%); median (interquartile range) duration was 9.2 (4.1–23.2) months. Median (95% confidence interval [CI]) OS from initiation of first systemic treatment was shorter in patients with USC (31.3 [27.7–34.3] months), CCC (29.2 [18.3–57.0] months), and carcinosarcoma (14.4 [7.9–53.1] months) versus the overall population (49.6 [43.9–52.0] months; table 2), as was median TFST from initiation of first systemic treatment (table 2).

Conclusion*In this large real-world study, patients with advanced USC, CCC, and carcinosarcoma had poorer survival outcomes than the overall AEC population, demonstrating an unmet need in these populations, such as the requirement for more effective therapies.