Low-grade endometrial cancer was defined as G1 and G2, and high-grade endometrial cancer was denoted as others; 13.3% (two cases) of samples from low-grade endometrial cancers were HER3-high at initial diagnosis, which increased significantly to 86.7% (13 cases) at recurrence (p < 0.0001; Additional file 7: Figure S2e). This evidence concerns the gene ERBB3 and endometrial cancer.