الفهرس 
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Abstract
Colorectal cancer (CRC) is the third most common cancer and the fourth most common cause of cancer-related death. Most cases of CRC are detected in Western countries, with its incidence increasing year by year. Adenocarcinoma constitutes the vast majority of colorectal cancers and represent 70% of all malignancies arising in gastrointestinal tract.
Adenomatous polyps of the colon and rectum are benign, but may be precursor lesions to colorectal cancer.The chance of having polyps is also increased in patients with a family history of colorectal polyps or colorectal cancer, including inherited disorders such as familial adenomatous polyposis.
Thioredoxin system comprised of thiorexin and NADPH dependent thioredoxin-1, is responsible for redox regulation of cells by controlling the apoptosis, proliferation and other vital processes of cells.The up-regulation of thioredoxin-1(Trx1) has been observed in various malignancies, which was associated with tumor angiogenesis and development.Thioredoxin-1 links to the process of angiogenesis which is a vital phenomenon for successful tumor development. Based on the studies, this association might be through the increasing of hypoxia-inducible factor-1 (HIF-1) and VEGF (Vascular endothelial growth factor) following the up-regulation of thioredoxin-1.
The aim of the present work is to determine the expression of thioredoxin-1 in colorectal carcinoma and adenomatous polyps and correlate its expression with other established prognostic parameters of colorectal carcinoma (age- sex- tumor site-shape-size-grade-stages-vascular invasion and necrosis).
The present work was undertaken on 40cases of colorectal adenocarcinoma and 30 cases of benign adenomatous polyps: Cases were collected between January 2017 and April 2018 from Pathology department, Medical research Institute, Alexandria University.
In our work,there was routine Hematoxylin and Eosin staining for diagnosis of adenomatous polyps and adenocarcinoma cases. Also there was immunohistochemical staining for thioredoxin-1which is considered positive if there isbrown staining in the cytoplasm or in the cytoplasm and nucleus of the stained cells.
Statistical analysis of the result was performed on 40 cases of colorectal adenocarcinoma and 30 cases of benign adenomatouspolyp cases.
In the present work,there was a statistically significant different in thioredoxin-1 expression between CRC and adenomatous polyps(p<0.001).
In adenocarcinoma cases,the difference of thioredoxin-1 expression was statistically significant as regards, age (p=0.001), grades (p=0.001), stages (p<0.001), vascular invasion (p=0.043). On the other hand, the difference of thioredoxin-1 expression was statistically non-significant as regards, sex (p=0.294), site (p=0.940), shape (p=0.478), size(p=0.561), tumor necrosis (p=0.248).
In benign adenomatous polyp cases, the difference of expression was statistically significant only in grade of dysplasia (p=0.002). Thioredoxin-1 expression is high in adenomatous polyp with high grade dysplasia. On the other hand,the difference of thioredoxin-1 expression was statistically non-significant as regards, sex (p=0.074), age (p=0.184), site (p=0.184), shape (p=0.287), size (p=0.254).
Therefore, from our study we concluded that, thioredoxin-1 expression is linked with an aggressive phenotype in colorectal adenocarcinoma and high grade of dysplasia in adenomatous polyps.