الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Oral cancer is the 11th most common malignancy in the world and the sixth most
common type among all head and neck cancers with an annual incidence of about half a million new cases and around 300,000 death each year (1%–2% of all cancer death). It represents about
85% of all head and neck cancers. Among all oral cancers, squamous cell carcinoma accounts
for 90% of them.
Field cancerization is a relatively new terminology in the field of cancer, it indicates
that when cancer develops in a tissue, a group of genetically altered clones of cells in adjacent
clinically normal tissue occur, which are prone to the development of synchronous and
metachronous tumors. The field cancerization theory also emphasizes the high probability of
recurrences in patients with head and neck squamous cell carcinoma.
Numerous factors have been implicated in the etiology of oral cancer. Through years,
the use of tobacco, alcoholic beverages, smokeless tobacco and betel quid were considered
well-known risk factors for oral squamous cell carcinoma development. However, minimal
worthy studies were performed to investigate the effect of cannabis smoking on oral cancer
development. In our study we aimed to investigate the changes that occur in the oral mucosa
of cannabis smokers and compare them to cigarette smokers and non-smokers.
Three groups of subjects were included in our study (33 in each group); cannabis and
cigarette smokers, cigarette smokers and non-smokers. The mucosal biopsy was examined by
routine H&E techniques. Furthermore, immunohistochemical expression of p53 was studied in all cases.
The present work demonstrated evident dysplastic and pre-dysplastic changes in H&E
stained sections. These were detected histologically in both smoker groups. These changes
were more pronounced in cannabis smokers’ group than cigarette smokers’ group. Moreover,
a statistically significant difference in p53 expression was present between non-smokers and
both smoker groups. However, p53 immunostaining was higher for cigarette smokers’ group
than cannabis smokers’ group.
It was evident that cigarette smoking and cannabis smoking both result in field changes
in the oral mucosa which were detectable in tissue sections. These changes, such as hyperplasia and dysplasia were more detectable in H&E sections of cannabis smokers than cigarette
smokers. However, positive p53 immunoexpression was lower in cannabis smokers than
cigarette smokers showing more field cancerization in the cigarette smokers’ group.