Predictive value of measuring p53 labeling index at the invasive front of oral squamous cell carcinomas

Many studies have revealed the frequency of p53 abnormalities in oral cancer. However, it reports only on the relation between clinicopathological findings and p53 expression, and there is no study to examine the relation to the p53 labeling index (p53-LI). The purposes of this study were to examine the correlation between p53 labeling index (p53-LI) at the invasive front of oral squamous cell carcinomas (OSCC) and clinicopathological findings by immunohistochemical staining, and to evaluate clinical significance of measuring p53-LI at the invasive front of OSCC. Sixty-six biopsy specimens of OSCC were randomly selected. Patient age, gender, primary sites, T category, N category, degree of differentiation and mode of cancer invasion were analyzed. p53 expression did not correlate significantly with the clinical findings. However, significant differences were found between p53-LI and the degree of cell differentiation (p < 0.05). The p53-LI of high-grade invasive tumors was significantly larger than that of low-grade invasive tumors (p < 0.05). The overall survival rate (OS) among low-scoring p53-LI cases was 75.5% whereas that for high-scoring p53-LI cases was 40.6%. The disease-free survival rate (DFS) among low-scoring p53-LI cases was 39.5% whereas that for high-scoring p53-LI cases was 76.1%. Patients with low-scoring p53-LI had a significantly worse prognosis than those with among high-scoring p53-LI (p < 0.05). Consequently, the measurement of p53-LI at the invasive front of OSCC is significant as one of the indicators of prognosis.