[Biology and relevance of stem cells in squamous head and neck cancer: latest insights and review of literature].

The initiation, growth, recurrence and metastasis of head and neck squamous cell carcinomas (HNSCC) and other cancers have recently been related to the presence of cancer stem cells (CSC). Cancer stem cells have some characteristics in common with tissue stem cells like unlimited self renewal and the expression of stem cell factors. CSC express specific markers that vary considerably depending on tumor type or tissue of origin--the discovery of an universal marker has not yet been made. Compared to the bulk tumor mass, CSC are less sensitive to chemo- and radiotherapy and also have a lower immunogenicity. Another concept that explains the seeding of metastases is the epithelial-mesenchymal transition of CSC. CSC-targeted therapies may change the prognosis of patients with HNSCC in the future. Recent knowledge on the role of CSC in HNSCC is reviewed, and known CSC markers as well as possible therapeutic targets are described.
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