The Risk of Oral Cancer among Different Categories of Exposure to Tobacco Smoking in Sri Lanka

Background: The global incidence of oral squamous cell carcinoma (OSCC) is on the rise with no improvement seen in survival rates. Tobacco consumption varies depending on geographic location, ethnicity and culture. The present case-controlled study aimed to determine the relative risk of OSCC for different tobacco consumption patterns in a selected Sri Lankan population. Methods: One hundred and five patients with histopathologically confirmed OSCC attending the National Cancer Institute (Apeksha Hospital) of Sri Lanka and 210 age and gender-matched controls from the community responded to an interviewer-administered questionnaire regarding their smoking and betel-quid chewing (with/ without smokeless tobacco) habits were included in the study. The odds ratios (OR) and 95% confidence intervals (CI) were calculated. p<0.05 was considered as statistically significant. Results: The overall risk of OSCC increased 2.93-fold for smokers. Those smoking two packets of cigarettes or more per day (OR=5.56; 95% CI-2.822-10.984; p=0.000) had more than double the risk of OSCC than those smoking 1-2 packets per day. Smoking for more than 20 years had a 3.4-fold risk of OSCC. Consumption of betel quid containing tobacco (smokeless tobacco) had a 4.26-fold higher risk for OSCC (OR=4.26; 95% CI-2.21-8.21; p=0.000), and the risk increased when all four ingredients (betel leaf, slaked lime, areca nut, and tobacco) were consumed together (OR=4.26; 95% CI-2.34-7.74; p=0.000). The combined effect from concurrent smoking and betel chewing emerged as the highest risk for OSCC (OR=15.34) which significantly exceeded the risks evident for the two habits practised in isolation from each other. Conclusions: Use of smokeless tobacco, consumption of all four ingredients together, duration of smoking, the number of cigarettes smoked per day and combined consumption of betel quid and smoking are significant risk factors in the development of OSCC among Sri Lankans.