Head and neck squamous cell carcinomas (HNSCCs) arise in the mucosal linings of the upper aerodigestive tract and are heterogeneous in nature. Risk factors for HNSCCs are smoking, excessive alcohol consumption, and the human papilloma virus. Conventional treatments are surgery, radiotherapy, chemotherapy, or a combined modality; however, no international standard mode of therapy exists. In contrast to the conventional model of clonal evolution in tumor development, there is a newly proposed theory based on the activity of cancer stem cells (CSCs) as the model for carcinogenesis. This "CSC hypothesis" may explain the high mortality rate, low response to treatments, and tendency to develop multiple tumors for HNSCC patients. We review current knowledge on HNSCC etiology and treatment, with a focus on CSCs, including their origins, identifications, and effects on therapeutic options.
Keywords: ABC, ATP-binding cassette transporters; ATC, amplifying transitory cell; Antineoplastic agents; BMI-1, B cell-specific Moloney murine leukemia virus integration site 1; Cancer stem cells; Cancer treatment; Carcinoma; EGFR, epidermal growth factor receptor; HIFs, hypoxia-inducible factors; Head and neck cancer; MDR1, Multidrug Resistance Protein 1; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; PI3K, phosphatidylinositol-4,5-bisphosphate 3-kinase; Squamous cell; TKIs, tyrosine kinase inhibitors.
© 2019 The Authors.