Expression of epidermal growth factor receptor and HER-2/neu in normal and neoplastic cervix, vulva, and vagina.

Monoclonal antibodies were used to localize immunohistochemically epidermal growth factor receptor and HER-2/neu in normal and neoplastic frozen tissue samples from the lower genital tract of women. In squamous epithelia of the cervix, vulva, and vagina, epidermal growth factor receptor and HER-2/neu both were expressed most strongly by basal keratinocytes. Expression of both of these cell surface molecules decreased as cells underwent differentiation toward the mucosal surface. In contrast, both epidermal growth factor receptor and HER-2/neu were expressed throughout the entire thickness of the epithelium by undifferentiated squamous cells in squamous metaplasia, raised condyloma, and carcinoma in situ. In 34 squamous cancers of the cervix, vulva, and vagina, all malignant cells were found to have moderate to heavy staining for epidermal growth factor receptor. Staining of 33 of these cancers for HER-2/neu was light, although one patient who presented with distant metastases had heavy staining for HER-2/neu. These data suggest that although overexpression of HER-2/neu in squamous cancers of the lower genital tract is a rare event, it may be associated with aggressive biologic behavior.