Prognostička vrijednost imunohistokemijske ekspresije 8-okso-7,8-dihidro-2'-deoksigvanozina u bolesnika s kolorektalnim karcinomom [Prognostic value of 8-oxo-7,8dihydro-2'-deoxyguanosine immunohistochemical expression in patients with colorectal cancer ]

Abstract: Role of the oxidative stress in the carcinogenesis of colorectal cancer is still unclear. 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG) is a marker of deoxyribonucleic acid (DNA) damage and a potential marker for carcinogenesis. The hypothesis of this study is that increased expression of 8-oxo-7,8-dihydro-2´- deoxyguanosine in colorectal cancer is associated with higher tumor stage and shorter overall survival. The aim of this study was to identify 8-oxodG by immunohistochemistry in tumor tissue and surrounding normal mucosa in patients with colorectal cancer and to find out if its expression correlates with survival, depending on the stage of the disease according to the IUCC classification. The study was conducted on samples of patients operated for colorectal cancer at the Department of Surgery, University Hospital Center Zagreb, between January 1999 and December 2000. A total of 146 patients were identified and 8 were excluded due to lack of clinical data on disease progress. The final results were thus obtained by analyzing data of 138 patients. The study proved the relationship between the presence of 8-oxodG and worse survival in patients who underwent colorectal cancer surgery. Higher percentage of 8-oxodG positive tumors cells correlated with advanced disease stage. A positive correlation of the intensity of 8-oxodG reaction with advanced disease stage was not found. This can be explained by the relatively small number of patients, especially after dividing the cohort along various stages of the IUCC classification. Larger prospective studies are therefore needed to explain the effect of oxidative stress on the process of carcinogenesis in patients with colorectal cancer