Clinical Relevance of Cotinine and Nicotine Levels as Tobacco Exposure Biomarkers in Oral Cancer Patients

Abstract

Introduction: Oral cancer is cause mainly due to habits of tobacco consumption and it is a major health hazard across the world. The death rate due to the disease is also very high. However, the association of tobacco exposure with stage of the disease and treatment outcome is not reported. Therefore, we assessed correlation between levels of tobacco exposure with the disease status and treatment outcome in oral cancer patients. Materials and Methods: Urine samples were collected from enrolled pre-therapeutic oral cancer patients (N=96), healthy individuals with tobacco habits (N=19) and healthy individuals without tobacco habits (N=14). Urinary nicotine and cotinine levels were analyzed as indicators of tobacco exposure by HPLC methods. Data was statistically analyzed using the SPSS statistics version 20.0. Results: Present study revealed that tobacco exposure levels were significantly higher in oral cancer patients and healthy individuals with tobacco habits as compared to healthy individuals without tobacco habits. Receiver Operating Characteristics (ROC) curve analysis revealed that tobacco exposure levels have a good discriminatory efficacy between healthy individuals without habit of tobacco and oral cancer patients as well as between healthy individuals without habit of tobacco and healthy individuals with habits of tobacco. Kaplan Meier survival curve analysis also revealed that patients who were having higher tobacco exposure levels at the time of diagnosis showed worse survival than patients who were having lower tobacco exposure levels. Conclusion: Tobacco exposure levels could be a simple, non-invasive and cost effective prognostic biomarker for management of oral cancer. Keywords: Tobacco exposure, Cotinine, Nicotine, HPLC, ELISA, Oral Cancer, Urinary biomarker.