TP53 and endometrial endometrioid carcinoma: Furthermore, subtyping HER2-negative tumors also finds significance in other body systems and tumor types, such as those of p53-aberrant high-grade endometrial endometrioid carcinomas, where the authors suggest that tumors with HER2-very-low expression may behave less aggressively than HER2-low tumors (p=0.045) [14].