Role of Tobacco in the Development of Head and Neck Squamous Cell Carcinoma in an Eastern Indian Population

Head and neck squamous cell carcinoma (HNSCC) accounts for about 30-40% of all cancer types in Indiaand the subcontinent in general. HNSCCs are primarily not hereditary, but rather a disease of older and middleaged adults. Many etiological factors like tobacco, alcohol and HPV infection are known to play importantroles. Eastern India, particularly Kolkata, has a population heavily exposed to various types of smoked andsmokeless tobacco, with only limited exposure to alcoholic beverages. Since there have been no previousepidemiological studies on tobacco as the main risk factor for head and neck carcinogenesis in Kolkata, we herecarried out a hospital based case control study in the city and its adjoin regions. Data from 110 patients diagnosedwith HNSCC and a similar number of matched control samples were analyzed using chi-square (χ2) test. Survivalstatus of the patients was also analyzed using the Kaplan-Meier method. A tobacco habit was significantlycorrelated with the incidence of HNSCC and persons with current addiction had a 2.17 fold increased risk ofcancer development. Dose-response relationships were seen for the frequency (p=0.01) and duration (p=0.02) oftobacco exposure with the risk. No significant difference in impact was found with smoked as opposed to smokelesstobacco in the development of the disease. Among HNSCC patients, significant poor survival in cases withtobacco habit than in those with no addiction and in cases with >10 years of addiction than in those with ≤ 10years of addiction. Our data suggest that tobacco in both smoked and smokeless forms is the most importantrisk factor for both development and prognosis of HNSCCs and may be a major source of field cancerization onthe head and neck epithelium in the eastern Indian population.