Association of Cancer Stem Cell Markers With Aggressive Tumor Features in Papillary Thyroid Carcinoma.

Background: Identifying accurate prognostic molecular markers for papillary thyroid carcinoma (PTC) is important because many patients with PTC may be erroneously considered to have low-risk tumors. Evidence is also accumulating to support the existence of cancer stem cells in PTC. Methods: Thirty controls and 167 patients with PTC were selected to establish a tissue microarray to investigate cancer stem cell marker expression in samples from an established pathological database. The protein expressions of CD44, CD133, epithelial cell adhesion molecule (EpCAM), CD45, and CD90 were evaluated by immunohistochemical assay in the tissue microarray. Results: The protein levels of CD44, CD133, and EpcAm were significantly increased in PTC tissue compared with tissue from the controls. A positive correlation was found between cancer stem cell markers and tumor, node, and metastasis staging. Conclusions: Among a subset of patients with PTC, cancer stem cells detected by immunohistochemistry can be used as prognostic markers to screen for potential tumor dissemination. Whether these cancer stem cell markers are potentially therapeutic targets and, thus, could be used for effective adjuvant treatment strategies - remains to be seen, and more data are needed.