Genetic Polymorphism of Glutathione S-transferases M1 and T1, Tobacco Habits and Risk of Stomach Cancer in Mizoram, India

Aim: The incidence of stomach cancer in Mizoram is highest in India. We have conducted a populationbased matched case-control study to identify environmental and genetic risk factors in this geographical area.
Methods: A total of 102 histologically confirmed stomach cancer cases and 204 matched healthy populationcontrols were recruited. GSTM1 and GSTT1 genotypes were determined by PCR and H. pylori infections weredetermined by ELISA.
Results: Tobacco-smoking was found to be an important risk factor for high incidenceof stomach cancer in Mizoram. Meiziol (local cigarette) smoking was a more important risk factor than othertobacco related habits. Cigarette, tuibur (tobacco smoke infused water) and betel nut consumption synergisticallyincreased the risk of stomach cancer. Polymorphisms of GSTM1 and GSTT1 genes were not found to be directlyassociated with stomach cancer in Mizoram. However, they appeared to be effect modifiers. Persons habituatedwith tobacco smoking and/or tuibur habit had increased risk of stomach cancer if they carried the GSTM1 nullgenotype and GSTT1 non-null genotype.
Conclusion: Tobacco smoking, especially meiziol is the important riskfactor for stomach cancer in Mizoram. GSTM1 and GSTT1 genes modify the effect of tobacco habits. This studyis a first step in understanding the epidemiology of stomach cancer in Mizoram, India.