Cancer Stem Cells in the Biology and Treatment of Head and Neck Squamous Cell Carcinoma

Abstract

Emerging evidence has demonstrated that the pathobiology of head and neck squamous cell carcinomas (HNSCC) is defined by the function of cancer stem cells. These cancer stem cells constitute a small fraction of the overall tumor cells, typically ranging between 1 and 5 % of the overall tumor mass. They share the properties of multipotency and self-renewal with physiological stem cells. However, cancer stem cells are endowed with high tumorigenic potential, which makes these cells an integral part of tumor initiation and progression toward metastasis. These findings have provided a strong rationale for targeted elimination of cancer stem cells in the treatment of patients with head and neck cancer. Recent studies demonstrated that the cancer stem cells are highly resistant to conventional chemotherapy, which may explain why so many head and neck cancer patients experience tumor recurrence. Therefore, the elimination of these cancer stem cells will likely require the development of therapies specifically targeted to these cells. In this chapter, we will review the evidence on head and neck cancer stem cells and the perivascular niche where these cells typically reside and will also discuss initial attempts to overcome resistance to treatment by combining debulking therapies with cancer stem cell-targeted therapies.