Asian Pacifc Journal of Cancer Prevention, Vol 12, 2011 3147 Tumor Markers and Biochemical Parameters in Colon Cancer Patients Before and After Chemotherapy Asian Pacifc J Cancer Prev, 12, 3147-3150 Introduction Of all patients with colorectal carcinoma, an estimated 2- 6% are below 40 years of age. Several reports have described the poor prognostic factors for the survival in young patients with colorectal carcinoma (Turkiewicz et al., 2001). Malignant tumours arising in the colorectal mucosal epithelium destroy extracellular matrices such as the basement membrane, eventually becoming advanced cancers metastasising to the liver and other distant organs (Liotta,1986). Carcinoembryonic antigen (CEA) is a 180 kDa oncofetal glycoprotein and a well-known soluble tumor marker. Although its presence in normal tissues is mainly limited to the large intestine, it is overexpressed in most gastrointestinal malignancies, lung cancer, breast cancer and thyroid cancer (Thompson et al., 1991; Ojima et al., 2006). Cancer antigen (CA)-15.3 is a tumor marker detectable in the serum, which recognizes a mucinous antigen of MUC-1 glycoprotein, initially recognized by the monoclonal antibodies DF3 and 115D8, but later cloned and characterized as CD227 (Symeonidisa et al., 2004). C-reactive protein (CRP) is an acute-phase reactant and a known indicator of the malignant potential of tumors. C-reactive protein (CRP) is a sensitive but nonspecifc systemic marker of infammation. CRP is produced mainly in the liver along with other acute-phase proteins in response to cytokines released by phagocytes during infection, trauma, surgery, burns, tissue infarction, advanced cancer and chronic infammatory conditions (Otterness, 1994; Gabay and Kushner, 1999; Gan et al., 2004; Pepys, 2005; Konstantinos et al., 2008; Demir et Division of Biochemistry, Health Sciences Faculty, Yuzuncu Yil University, Van, Turkey *For correspondence: gurtugba@hotmail.com Abstract Objectives: Tumor markers and biochemical parameters were investigated in patients suffering from colon cancer and in volunteer healthy persons. Design and Methods: Biochemical analyses of erythrocyte enzymes and serum values for series of established tumor markers were conducted for 40 patients diagnosed with colon cancer, before and after chemotherapy, and 29 healthy volunteers between 2008 and 2009. Results: Activities of catalase and carbonic anhydrase were lower in sick than healthy groups (p<0.05) before and after chemotherapy, while alkaline phosphatase and creatinine were increased. The patients with colon cancer showed signifcant (p<0.05) elevation of CRP, fbrinogen, CA125, AFP, and decrease in ferritinin, before but not after therapy. Conclusion: The results obtaining from this investigation can be useful for colon cancer risk assessment. Keywords: Colon cancer - ALT - AST - carbonic anhydrase - catalase RESEARCH COMMUNICATION Tumor Markers and Biochemical Parameters in Colon Cancer Patients Before and After Chemotherapy Tuğba Gür 1* , Halit Demir 2 , M Çetin Kotan 3 al., 2010). It is known that when oxidative stress increases, damage may occur in the DNA sequence leading to cancer and other diseases as a result of the deterioration in the balance between free radicals and antioxidants (Halliwell, 2007). Antioxidant potential in all cases of gastrointestinal tract cancer has been unbalanced which has lead to increase in reactive oxygen species action and enhancement of lipid peroxidation and cancer procoagulant generation. Catalase subsequently reacts with hydrogen peroxide which was produced by SOD, and decomposes it into water and molecular oxygen (Skrzydlewska et al., 2003; Hwang et al., 2007; Demir et al., 2010). CA is a member of the alfa-family of carbonic anhydrases of zinc metalloenzymes that catalyze the reversible hydration of carbon dioxide to carbonic acid (Sly and Hu, 1995; Demir et al., 2010). In this investigation, we aimed to determine possible changes of some tumor markers (CEA, CA125, CA19–9, CA15–3 and AFP) before and after chemotherapy and some biochemical parameters (glucose, albumin, globulin, ferritin, ALT, AST, CRP, LDH, creatinin, alkaline phosphatase, amylase, fbrinogen, carbonic anhydrase and catalase) in a series of colon cancers in a relatively high incidence region of Van, Turkey. Materials and Methods In this study totally 40 patients diagnosed with colon cancer and 29 healthy volunteers between 2008 and 2009 used as material for examinations in Yuzuncu Yil University, Faculty of Medicine, Department of Medical