FOXA1 Expression by Immunohistochemistry in Carcinosarcomas of the Endometrium and Ovary/Fallopian Tube

FOXA1, a transcription factor essential for the binding of other transcription factors on chromatin, is associated with hormone receptor-associated cancers, such as breast and endometrial cancer. It is also considered an antagonist of epithelial-to-mesenchymal transition (EMT). In endometrial cancer, FOXA1 is considered a tumor suppressor; in carcinosarcoma, one of the most aggressive and rare subtypes of endometrial cancer, thought to be derived through an EMT mechanism, FOXA1 has not been studied. Thus, the aim of this study was to investigate the possible expression of FOXA1 in carcinosarcomas, and its correlation with clinicopathologic factors. This was a retrospective study of 31 patients diagnosed with carcinosarcomas of the uterus or the adnexa. Histologic and clinical factors were correlated with the immunohistochemical expression of FOXA1. FOXA1 was expressed by 38.7% of the carcinomatous components and 16.1% of the sarcomatous components. FOXA1-positive sarcomatous components were seen only with positive carcinomatous components (P=0.004). FOXA1 expression was not associated with age, primary tumor site, stage, metastases, overall survival, or tumor relapse. FOXA1 expression in the carcinomatous component was associated with an absence of lymphovascular invasion or the presence of heterologous components. FOXA1 expression in the sarcomatous component was associated with rhabdomyosarcoma, rather than the chondrosarcoma heterologous component. Carcinosarcomas harbor FOXA1 expression, although it is in their carcinomatous rather than sarcomatous components, suggesting a possible role of FOXA1 in the EMT of carcinosarcomas. FOXA1 shows no prognostic significance in this tumor group.