Aim: To study the relationship between the pathogenesis of lung cancer and antioxidant status and acidicmedia by measuring the activities of erythrocyte catalase (CAT) and carbonic anhydrase (CA). Methods: A totalof 26 patients with lung cancer and 15 healthy individuals were included in the study. The CAT and CA activitiesof erythrocytes were defined. The catalase (CAT) activity of erythrocytes was measured using Aebi`s method.Carbonic anhydrase (CA) activity was analyzed by CO2 hydration. Results: It was found that erythrocyte CAand CAT activities were significantly lower in patients with lung cancer compared to controls (p<0.05). Of the 26patients with lung cancer, seven (26.9%) had metastasis, and the CA and CAT levels in patients with metastasiswere significantly decreased (p=0,0001). Conclusions: Development of oxidative stress due to lung cancer maybe related to the balance between prooxidant and antioxidant reactions. Catalase may have a preventive effectfor malignant lung cancers and the gene of the antioxidant enzymes may be one of the anti-oncogenes, andinactivation of one of these genes in the process of carcinogenesis may lead to tumor development. This maybe an explanation for the very low levels of antioxidant CAT in patients with lung cancer compared to healthyindividuals. Carbonic anhydrase (CA) in tumor cells may be an indicator of the acid-base balance in lung cancer.Decreased levels of CA in patients with lung cancer may provide a convenient media for tumor development,growth and metastasis by creating an acidic media.
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