Background: Oral cancer is the third most common malignancy in Saudi Arabia, the highest incidence ofwhich is reported from Jazan province. The objective of this study was to evaluate the association of variouslocally used substances, especially shamma, with oral cancer in the Jazan region of Saudi Arabia. Materials and
Methods: A hospital-based case-control study was designed and patient records were scanned for histologicallyconfirmed oral cancer cases. Forty eight patients who were recently diagnosed with oral cancer were selected ascases. Two healthy controls were selected for each observed case and they were matched with age (+/- 5 years)gender and location. Use of different forms of tobacco such as cigarettes, pipe-smoking and shamma (smokelesstobacco)was assessed. Khat, a commonly used chewing substance in the community was also included. Descriptiveanalysis was first performed followed by multiple logistic regression (with and without interaction) to deriveodds ratios (ORs) and 95% confidence interval (CIs).
Results: Mean age of the study sample (56% males and44% females) was 65.3 years. Multinomial regression analysis revealed that shamma use increased the odds ofdeveloping oral cancer by 29 times (OR=29.3; 10.3-83.1). Cigarette (OR=6.74; 2.18-20.8) was also seen to have aneffect. With the interaction model the odds ratio increased significantly for shamma users (OR=37.2; 12.3-113.2)and cigarette smokers (OR=10.5; 2.88-3.11). Khat was observed to have negative effect on the disease occurrencewhen used along with shamma (OR=0.01; 0.00 - 0.65).
Conclusions: We conclude that shamma, a moist form ofsmokeless tobacco is a major threat for oral cancer occurrence in the Jazan region of Saudi Arabia. This studygives a direction to conduct further longitudinal studies in the region with increased sample size representingthe population in order to provide more substantial evidence.