الفهرس 
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Abstract
Colorectal cancer is a major cause of morbidity and mortality throughout the world. Over 1.8 million new colorectal cancer cases and 881,000 deaths are estimated to occur in 2018. It is the third most common cancer worldwide after lung and breast cancer and the second most common cause of death after lung cancer.
Neoplastic (adenomatous) colorectal polyps are benign tumors that originate from the mucus-secreting colonic epithelial cells. Adenomatous polyps are common, especially in western countries, occurring in the United States, in 20–40% of screening colonoscopies in people older than 50 years of age. In people younger than 50 years of age, 12% of women and 24% of men are found to have an adenoma on a screening colonoscopy. In women and men older than 80 years, the rates increase to 27% and 40%, respectively.
Cyclooxygenase 2 (COX2), an inducible form of the enzyme that catalyzes the first step in the synthesis of prostanoids, is associated with inflammatory diseases and carcinogenesis, which is suspected to promote angiogenesis and tissue invasion of tumors and resistance to apoptosis. Meanwhile, COX2 contributes to immune evasion and resistance to cancer immunotherapy, which plays a crucial role in the innate and adaptive immune response. The activity of COX2-PGE2-EP signal pathway can suppress Dendritic cells (DCs), natural killer (NK), T cells, type-1 immunity excluding type-2 immunity which promote tumor immune evasion. COX2 and the prostaglandin cascade play important roles in the “inflammogenesis of cancer”.
HER2 is a protein with tyrosine kinase activity encoded by the cellular oncogene ERBB2, which is located on chromosome 17q21. HER2 was localized mainly on the membrane of cancer cells, and HER-2-positive cells showe brownish yellow granules on the membrane. HER2 is overexpressed in a wide variety of tumors, especially breast, gastric, ovarian, and colorectal cancers.
The aim of this study is to explore and validate the expression of COX2 and HER2 in colorectal cancer and adenomatous polyps and their correlation with the prognostic parameters.
The present work was undertaken on 50 cases of colorectal adenocarcinoma, 30 cases of benign adenomatous polyp and 20 Cases of normal colorectal tissue specimens as a control group. Cases were collected between August 2019 and November 2020 from Pathology department, Medical research Institute, Alexandria University.
In the current work, there was routine Hematoxylin and Eosin staining for diagnosis of adenomatous polyps and adenocarcinoma cases. Also there was immunohistochemical staining for COX2 and HER2 which are considered positive if there is brownish staining in the cytoplasm or in the membrane respectively.
In the present work, there was a positive significant correlation between COX2 expression and the three studied groups (p<0.001).
In adenocarcinoma cases, there was a positive significant correlation between COX2 expression and the following: tumor size (p=0.026), grades (p=0.027), vascular invasion
(p=0.023), lymph node metastasis (p=0.028) and stages (p<0.008). On the other hand, there was no significant correlation between COX2 expression and the following: the gender (p=0.055), age (p=0.083), site (p=0.784) and shape (p=0.683).
In benign adenomatous polyp cases, there was a positive significant correlation between COX2 expression and the following: polyp size (p=0.007) and grade of dysplasia (p=0.034). On the other hand, there was no significant correlation between COX2 expression and the following: gender (p=1.000), age (p=0.846), site (p=0.947) and shape (p=1.000). COX2 expression is high in adenomatous polyp with polyp size more than 1 cm and high grade dysplastic polyp.
In control group cases, there was no significant correlation between COX2 expression and the following: gender (p=0.613) and age (p= 1.000).
In the present work, there was a positive significant correlation in HER2 expression between the three studied groups (p<0.001).
In adenocarcinoma cases, there was a positive significant correlation between HER2 expression and the following: tumor size (p=0.017), grades (p=0.034), vascular invasion (p=0.033), lymph node metastasis (p=0.021) and stages (p<0.043). On the other hand, there was no significant correlation between HER2 expression and the following: gender (p=0.215), age (p=0.548), site (p=0.394) and shape (p=0.858).
In benign adenomatous polyp cases, there was a positive significant correlation between HER2 expression and the following: polyp size (p=0.044) and grade of dysplasia (p=0.049). On the other hand, there was no significant correlation between HER2 expression and the following: gender (p=0.511), age (p=1.000), site (p=0.963) and shape (p=.989). HER2 expression is high in adenomatous polyp with polyp size more than 1 cm and high grade dysplastic polyp.
In control group cases, there was no significant correlation between HER2 expression and the following: gender (p=0.512) and age (p= 1.000).
In the present work, there was a statistically significant correlation between COX2 and HER2 expression in colorectal adenocarcinoma cases and adenomatous polyp cases but not significant in normal colorectal cases p=0.016), (p=0.048) and (p=0.161) respectively.
Therefore, from the present study we concluded that, expression of COX2 and HER2 is correlated with large tumor size (regarding COX2), moderately to poorly differentiated tumor, lymph node metastasis, vascular invasion and higher tumor stage in colorectal adenocarcinoma and large polyp size (regarding COX2) and high grade of dysplasia in adenomatous polyps.