AbstractThe incidence of endometrial cancer is rising. Measures to identify women at risk and to detect endometrial cancer earlier are required to reduce the morbidity triggered by the aggressive treatment required for advanced endometrial cancer. We developed the WID‐EC (Women's cancer risk IDentification‐Endometrial Cancer) test, which is based on DNA methylation at 500 CpG sites, in a discovery set of cervical liquid‐based cytology samples from 1086 women with and without an endometrial cancer (217 cancer cases and 869 healthy controls) with a worse prognosis (grade 3 or ≥stage IB). We validated the WID‐EC test in an independent external validation set of 64 endometrial cancer cases and 225 controls. We further validated the test in 150 healthy women (prospective set) who provided a cervical sample as part of the routine Swedish cervical screening programme, 54 of whom developed endometrial cancer within 3 years of sample collection. The WID‐EC test identified women with endometrial cancer with a receiver operator characteristic area under the curve (AUC) of 0.92 (95% CI: 0.88‐0.97) in the external set and of 0.82 (95% CI: 0.74‐0.89) in the prospective validation set. Using an optimal cutoff, cancer cases were detected with a sensitivity of 86% and a specificity of 90% in the external validation set, and a sensitivity and specificity of 52% and 98% respectively in the prospective validation set. The WID‐EC test can identify women with or at risk of endometrial cancer.