Expression of the Na(+)/I(-) symporter in invasive ductal breast cancer.

The function of the sodium iodide symporter (Na(+)/I(-), (NIS), a membrane protein that mediates iodide transport into cells, is the best described in the thyroid cells. NIS is also found in mammary cells during lactation and in breast carcinoma cells. The aim of this study was evaluation of incidence and grade of NIS expression in invasive ductal breast cancer. Immunohistochemistry using a panel of antibodies against NIS was carried out in surgical paraffin-embedded tissue obtained from 50 patients with invasive ductal breast carcinoma. NIS expression was found in 45 (90%) cases. The demonstration of NIS expression in breast carcinoma cells may provide a novel approach to its diagnosis and treatment.