Overexpression of HER-2/neu in endometrial cancer is associated with advanced stage disease.

Prior studies have shown that overexpression of HER-2/neu occurs in one third of breast and ovarian cancers and that overexpression is associated with poor prognosis. We used a monoclonal antibody to assess immunohistochemically the level of HER-2/neu expression in normal and malignant endometrium. In 24 normal endometrial samples light to moderate (1+ to 2+) staining for HER-2/neu was seen in the glands, and there was no variation in intensity of staining during the menstrual cycle. Among 95 endometrial adenocarcinomas, nine (9%) were found to have heavier staining for HER-2/neu than was seen in normal endometrium (3+). High expression of HER-2/neu was found in 27% of patients with metastatic disease compared with 4% of patients with disease confined to the uterus (p less than 0.005). High HER-2/neu expression also was associated with absence of estrogen receptor (p less than 0.005) and with increased mortality from cancer. Further studies are needed to determine the significance of HER-2/neu overexpression in endometrial cancer.