Tissue levels of oxidative stress markers and antioxidants in colorectal cancer patients.

The role of reactive oxygen species in the development of cancer has become well recognized in recent years; however, evidence for a link between oxidative stress and cancer risk has not been fully explored. One of the major cancers whose number of cases has increased significantly in recent years is colon and rectal cancer, which has the second highest mortality rate in Libya. Forty subjects were divided into three groups (20 tumors from colorectal cancer patients, adjacent surrounding tumor tissues, and 20 adjacent normal tissues). Evaluation of oxidative stress indices in the samples was performed by analyzing enzymatic and non-enzymatic parameters including the activity of glutathione peroxidase and catalase as antioxidant enzymes, reduced glutathione as an antioxidant, malondialdehyde MDA levels as an oxidative damage product, nitritc oxide content NO as an inflammatory marker, and total thiols as a measure of redox status. MDA and NO levels were significantly higher in tumor tissues than in adjacent healthy tissue. Also, the surrounding tumor tissue exhibited higher MDA and NO levels compared with control tissues. The oxidant and antioxidant levels in the tumor was significantly lower than those in the surrounding tumor tissue and control healthy tissue. The results suggest that oxidant and antioxidant parameters can be used as indicators of an imbalance in humans, and as this imbalance increases, the human body may be vulnerable to developing cancer. [ABSTRACT FROM AUTHOR]