Estudo do polimorfismo genético de ADH1BR48H e suas associações ao câncer de cavidade oral.

Abstract

Oral cavity cancers are considered a public health problem throughout the world and represent the sixth most common cancer. The main risk factors include tobacco, alcohol, micronutrient deficiency and the human papillomavirus (HPV). The metabolism of alcohol depends on the alcohol dehydrogenase (ADH), a family of enzymes with high frequency of genetic polymorphisms that give different individuals a wide range of susceptibility to metabolites. Thus, different genetic polymorphisms in ADH can interfere with the individual risk of cancer associated with alcohol consumption. The aim of this case-control study was to evaluate the frequency of SNP (SNP: single nucleotide polymorphism) in ADH1B gene in 61 patients with cancer of the oral cavity and in 66 healthy controls. The molecular study employed methods including polymerase chain reaction (PCR) associated to restriction fragment analysis (RFLP). The frequencies obtained for the genetic polymorphisms were calculated and compared in both groups, as well as the possible association between these polymorphisms and the characteristics of tumors. The results showed a higher prevalence of these tumors in the male population (74.3%), at ages above 45 years (88.5%), smokers (85.2%) and alcoholic (82.0%). Among the prognostic factors evaluated, the advanced stage (III and IV) was observed in 73.8% of cases and the involvement of regional lymph nodes in 39.3% of cases. Allele frequencies for ADH polymorphism R48H on group of cases were L = 82.8 and A = 17.2%, while in the control group were 79.4% and G = A = 20.6%. The genotypic frequencies obtained for the case group were AA = 16.0%; GA = 2.0% and GG = 81.0%, while for the control group, genotype frequencies were AA = 15.0%; GA = 12.0% and GG = 74.0%. The overall survival evaluated for the group was 49.9%. Significant differences in allele and genotype frequencies were observed between the groups or between the prognostic aspects evaluated. Epidemiological data from the oral cavity cancer have shown worrying trends, stressing the importance of promoting more studies related to this particular type of cancer.