RESUMO
BACKGROUND: Lower lip squamous cell carcinoma (LLSCC) is an oral cancer that has distinct epidemiology and etiopathogenesis. Although risk factors for this neoplasia are acknowledged, few studies have investigated the molecular basis of its development and behavior. METHODS: Expression of p53 and p21(WAF1/CIP1) was examined by immunohistochemistry of archived tissue from 21 specimens of LLSCC. Differences in this expression between the whole tumor (WT) and the invasive front (IF) as well as correlation between p53 and p21(WAF1/CIP1) expression were analyzed. RESULTS: p53 and p21(WAF1/CIP1) were overexpressed at the IF of LLSCC. The expression of both proteins was higher at IF than at WT. No correlation was observed between p53 and p21(WAF1/CIP1) expression. CONCLUSIONS: Our results indicate that p53 and p21(WAF1/CIP1) overexpression is important in LLSCC pathogenesis, reinforce that IF is the most important area for tumor behavior, and support that p53-independent mechanisms should be involved in the expression of p21(WAF1/CIP1).