Avaliacao de polimorfismos nos genes XPD e XRCC3 em carcinomas orais de celulas escamosas

Oral squamous cell carcinoma (OSCC) is an important cause of morbidity and mortality worldwide despite recent advances in treatment. There are several studies aiming to find markers that may improve the assessment of this disease prognosis. Studies about genetic polymorphisms have gained prominence due to their influence on individual susceptibility to cancer development. The aim of this study was to evaluate the association between the frequency of polymorphisms XPD Lys751Gln and XRCC3 Thr241Met and clinicopathological features of OSCC cases, including age, sex, presence or absence of metastases, and histological grading of malignancy according to Bryne (1998). Sample consisted of 54 cases of OSCC and 40 cases of inflammatory fibrous hyperplasia (IFH). OSCC cases were classified as low or high grade. DNA samples were previously extracted from paraffin blocks. Genotypes for each case were determined through PCR-RFLP (polymerase chain reaction - restriction fragment length polymorphism). Results were analyzed by Fisher s exact test and Chi-square test and the odds ratio was calculated considering p < 0.05 to indicate statistical significance. For XPD, Lys/Gln genotype was more common in IFHs (n=28; 70%) than in OSCCs (n=24; 44.4%) (OR: 0.3; p<0.05). Frequency of Gln allele was higher in high-grade lesions when compared to low grade lesions (0.48 and 0.21, respectively) (OR: 3.4; p<0.05). For XRCC3, Met allele was more common in OSCC than in IFH (0.49 and 0.35, respectively) (OR: 2.6; p<0.05). Met/Met genotype was associated with presence of metastases (OR: 8.1; p<0.05). There was no statistically significant association between the genotypes and the age or sex of patients. In the present sample, the higher frequency of XPD Gln allele in IFH reveals a possible protective role of this variant against the development of OSCC. However, its association with high-grade lesions indicates that this allele could influence the tumor progression after the neoplasia development. The presence of XRCC3 Met allele, in turn, seems to contribute to the development of OSCC and metastases