Introduction: ALDH2 is an enzyme involved in major oxidative pathway of alcohol metabolism while GSTM1 is a drug-metabolizing enzyme of acetaldehyde. It has been reported that the mutant ALDH2 allele and the absence of GSTM1 contributes to increased oral cancer risk due to reduced acetaldehyde metabolism. This study aims to determine ALDH2 and GSTM1 polymorphisms and its association with oral cancer risk. Method: An unmatched case-control study was conducted using 163 oral cancer patients and 87 non-cancer subjects selected from the OCRCC database. ALDH2 and GSTM1 genotypes were determined using PCR-RFLP from peripheral blood. Multiple logistic regression was employed to assess association between polymorphisms and oral cancer risk. Results: Most common risk habit was betel-quid chewing (44.0%), followed by smoking (30.4%) and alcohol drinking (29.6%). The prevalence of ALDH2 polymorphism is only 5.7%, while GSTM1 null is seen in 51.2%. Alcohol drinking and the combination of ALDH2 polymorphism and alcohol consumption is significantly associated with increased risk of oral cancer (p < 0.001). Discussion: In this population, although the prevalence of alcohol consumption is low compared to other populations, alcohol drinking has been found to significantly increase oral cancer risk, even after adjusting for confounding factors (age, gender and ethnic) (aOR 6.8, 95% CI 2.6, 18.1). The prevalence of ALDH2 polymorphism was found to be much lower compared to other Asian population such as the Japanese and Taiwanese. In relation to oral cancer risk, no significant association was seen for both the polymorphisms of ALDH2 and GSTM1. However, when analysis was done for the combination of ALDH2 polymorphism and alcohol consumption, those who concurrently exhibit ALDH2 polymorphism and consumed alcohol was found to be 6 times more likely to develop oral cancer (aOR 6.6, 95% CI 2.4, 17.9). No such association was observed for the combination of GSTM1 polymorphism and alcohol consumption. In conclusion, alcohol consumption is a significant independent risk factor for oral cancer among Malaysians while ALDH2 polymorphism together with the habit of alcohol drinking also confers an increased risk for oral cancer.

Introduction: Dietary intake has been hypothesized to be associated with various diseases including oral cancer. According to studies worldwide, imbalanced diet and nutrient deficiency have been attributed to promote oral malignancies. However, the function of specific nutrients in preventing oral cancer remains largely undefined. This study aims to investigate the association between intake of retinol and vitamin C with the risk of oral cancer. Materials and methods: Dietary intake data was collected from 8 participating hospitals throughout Malaysia using a validated foodfrequency questionnaire (FFQ). Intake of retinol and vitamin C were computed using the Nutriemart software. This case-control study included 150 cases and 150 controls matched for age, gender and ethnicity.The association between micronutrients, risk habits and oral cancer was analysed using Pearson Chi-Square test and multiple logistic regression. Results: Significantly more controls were found to consume retinol (27.3%) and vitamin C (83.3%) above the Recommended Daily Allowance (RDA) as compared to cases (10.7% and 72.0%, respectively). Among risk habits, only cigarette smoking was found to have an inverse association with vitamin C (p = 0.021) where as no risk habits were found to be associated with retinol intake. After adjusting for confounding factors, only retinol intake was found to be inversely related to the risk of oral cancer (aOR 0.272, 95%CI 0.135-0.548). Discussion: This study suggests that vitamin C appears to reduce risk of oral cancer and this relationship is weakened after adjusting for risk habits. Meanwhile, retinol intake proves to provide protection against oral cancer up to 72.8% independent of risk habits practiced.