Abstract B87: A study of tobacco exposure and oxidative stress related biomarkers in oral cancer

Oral cancer is the leading malignancy in India, with tobacco playing a major role in the etiology. The aims of the present study was (i) to assess tobacco exposure related biomarkers in controls, patients with oral precancers (OPC) and oral cancer patients, (ii) evaluate nitric oxide [as NO₂+NO₃] and antioxidant enzymes in the subjects and (iii) to evaluate correlation between tobacco exposure and oxidative stress related biomarkers in oral cancer patients.

Healthy individuals (n=90) were grouped into without habit of tobacco (NHT, n=30) and healthy individuals with habit of tobacco (WHT, n=60). Oral cancer patients with a tobacco habit were classified into abstinence (n=62) and non-abstinence (n=64) groups according to status of tobacco habits at the study time. Urinary nicotine and cotinine levels were analyzed by HPLC using a UV detector. Plasma NO₂+NO₃, superoxide dismutase (SOD) and catalase levels were estimated by spectrophotometry.

The Odds Ratio (OR) analysis indicated positive associations of both smoking and chewing habits of tobacco with high risk of development of oral cancer. Urinary nicotine and cotinine were significantly elevated in WHT, patients with OPC and oral cancer patients as compared with the NHT group. Levels of urinary nicotine and cotinine were also higher in the non-abstinence group with oral cancers than abstinence group. Mean plasma NO₂+NO₃ levels were elevated in patients with OPC and oral cancer patients as compared to the controls. Erythrocyte SOD and catalase levels were higher in WHT and patients with OPC as compared to NHT. The erythrocyte SOD and catalase activities were lower in oral cancer patients than patients with OPC. Person’s correlation analysis revealed that the changes in erythrocyte SOD and catalase activities were positively associated with urinary nicotine values. The alterations in plasma NO₂+NO₃ levels were negatively associated with changes in erythrocyte SOD activities.

The results confirmed that (i) tobacco chewing and smoking habits are prominent risk factors for development of oral cancer in the western part of India (Gujarat). (ii)Urinary nicotine and cotinine levels can be helpful for screening programs for oral cancer. (iii) The alterations in antioxidant activities were associated with production of nitric oxide in oral cancer, which may have significant role in oral carcinogenesis.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B87.