الفهرس 
EPIDEMIOLOGYOnly 14 pages are availabe for public view
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Abstract
Head and neck cancer accounts for more than 780,000
cases annually worldwide.
• The main risk factors include tobacco and alcohol use and
HPV virus infection.
• Most of patients present with late stage disease with the
cure rates reach only 30%.
• Despite aggressive treatments with combinations of surgery,
radiation and chemotherapy, little progress has been made
towards better outcomes.
• In recent years, many studies have shown that some types
of tumors are characterized by the presence of cells with
stem-like characteristics, called cancer stem cells (CSCs).
These are considered cells that initiate the tumor and are
probably responsible for tumor recurrence.
• Cancer stem cells can be identified via surface markers,
CD44 is a type I transmembrane glycoprotein expressed in
several cell types of mesenchymal and neuroectodermal
origin. CD44 functions as a major adhesion molecule and
in the cellular internalization of hyaluronic acid.
• Numerous studies have highlighted the connection between
CD44, hyaluronic acid, and the PI3K–Akt system, whose
stimulation leads to phosphorylation of Akt (also known as
Summary and Conclusion
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protein kinase B). p-Akt positively involved in the
processes of cell survival and in the development of
resistance to chemotherapy.
• Also Ki 67 as a proliferation marker was investigated for
its prognostic value in pharyngeolaryngeal SCC.
• Our analysis of the prognostic value of both CD44 and KI
67 in the laryngeal and hypopharyngeal SC,by determining
the rate of expression of Cancer Stem Cells marker CD44
& Ki-67 proliferation marker in tumor specimen of
HNSCC, correlating data with the TNM staging, response
rate to conventional chemoradiation therapy or definitive
radiotherapy and the progression free survival of those
patients revealed that CD 44 is related to worse T stage,
more resistance to chemo-radiotherapy and worse
prognosis in terms of progression free survival.
• While KI 67 showed no relation to either the
histopathological features, response to treatment or
progression free survival, This may be explained by the
type of therapy, where the patients treated by surgery show
KI 67 prognostic value other than those patients treated
with chemo- radiotherapy.