الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Head and neck cancer accounts for 5% of the total malignant tumours. Squamous cell carcinoma is the most common form of head and neck cancer, it accounts for 95 of head and neck cancers. The relative survival rates for patients with head and neck cancers globally are among the lowest of all major cancers. Thus, head and neck cancers pose a major health problem worldwide. EBV-associated tumours tend to occur in the head and neck region as the oropharyngeal epithelium is the main site of EBV proliferation after infection. Epstein-barr virus (EBV) is an ubiquitous human herpes virus. It is a member of the gamma herspesvirinea subfamily. EBV genome consists of linear, double stranded DNA molecule of about 172.000 kb. Antibodies to certain EBV-specific antigens are detectable in large percentage of the general population. EBV is commonly transmitted by infected saliva. Air-borne or blood-borne transmissions are not important routes of infection. EBV-primary infection is usually asymptomatic or causes infectious mononucleosis (IM). Firstly, EBV infects and replicates in oropharyngeal epithelial cells with shedding of virus particles into the saliva. Then, it infects ?-cells where it persists in a latent state. EBV has been associated with a wide spectrum of benign and malignant diseases including: Burkitt’s lymphoma, Nasopharyngeal carcinoma, Hodgkin’s disease, T-cell lymphoma, B-cell lymphoma in AIDs patients and transplant recipients, leiomyosarcoma and oral hairy leukoplakia in AIDs patients, gastric adenocarcinoma, cervix cancer and childhood smooth muscle tumours. EBV has been detected in oral squamous cell carcinoma. It has been also associated with other epithelial cancers of head and neck region including: carcinoma of the palatine tonsil, supraglottic laryngeal carcinoma and salivary gland cancer. The diagnosis of EBV infection in head and neck cancers is based on antigen demonstration in tissue biopsies using several methods including immunohistochemical staining method. Serologic assays may aid in early diagnosis of occult cancers. The aim of this study was to detect EBV in head and neck squamous cell carcinoma by: 1- Studying the presence of antibodies in serum against EBV and their titers in head and neck squamous cell carcinoma. 2- Demonstration of EBV antigen in tissue biopsy specimens obtained from cases with head and neck squamous cell carcinoma by immunohistochemical staining method. 3- Comparing the significance of EBV antibody titer in serum versus EBV antigen detection in tissue biopsy specimens. This study included 50 cases with head and neck squamous cell carcinoma and 45 normal healthy individuals, matching for age and sex as control group. Biopsy specimens were taken from all the cancer cases under general anaesthesia. Biopsies of normal tissue were taken from the safety margin of the tumour tissue and from healthy volunteers matching for sites, age and sex as a control group. Half of each tissue section from each case were formalin fixed, paraffin embedded and stained with haematoxylin and eosin to be screened by means of light microscope for diagnosis. Serial paraffin sections were processed to detect the EB viral antigen using the labeled streptavidin-biotin immunoperoxidase staining method (LAB). For serological study five ml venous blood were collected from each case. All serum samples were tested for the detection of EBV IgG by ELISA test to compare its results with the immunohistochemical findings