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Erschienen in:
01.04.2009 | Breast Oncology
Endogenous NIS Expression in Triple-Negative Breast Cancers
Erschienen in: Annals of Surgical Oncology | Ausgabe 4/2009
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Background
The sodium iodide symporter (NIS) mediates iodide transport into cells and has been identified in approximately 70% of breast cancers. Functional NIS expression raises the possibility of using 131I for therapeutic targeting of tumor cells. Treatment of triple-negative breast cancers [estrogen/progesterone receptor-negative and HER2-negative (ER−/PR−/HER2−)] is primarily limited to chemotherapy. Our aim was to characterize NIS expression in this subset of tumors.
Methods
Archival tissue sections from 23 women with triple-negative breast cancer were analyzed for NIS expression using immunohistochemical methods and an anti-human NIS antibody. Tumors were evaluated for the presence of plasma membrane immunoreactivity. One patient with a NIS-expressing positive tumor underwent 123I scintigraphic imaging with dosimetric analysis.
Results
Fifteen cases (65.2%) demonstrated NIS-positivity with 11 tumors (47.8%) exhibiting strong expression. Plasma membrane immunoreactivity was observed in four breast cancers and was equivocal in another four tumors. Tumor-specific radioiodide uptake was demonstrated by 123I scintigraphy in a patient with a large primary breast cancer unresponsive to neoadjuvant therapy. The tumor concentrated 2.05, 1.53, and 1.96 times more isotope than normal breast tissue at 1, 5, and 21 h. The relative increased uptake is consistent with positive NIS expression in the tumor on definitive surgery; however, the cumulative concentration in the tumor was not sufficient to achieve a therapeutic effect, had the isotope been 131I.
Conclusions
NIS is strongly expressed in a significant proportion of triple-negative breast cancer cells, suggesting a potential role for NIS-directed 131I-radioablative strategies in this patient population.