Evidence based demonstration of the concept of 'field cancerization' by p53 expression in mirror image biopsies of patients with oral squamous cell carcinoma - an immunohistochemical study.

OBJECTIVE: The main rationale for treatment failure and death of the patients with oral squamous cell carcinoma (OSCC) is loco-regional recurrence, development of second primary tumor (SPT) and metastasis, which could be well explained by concept of field cancerization. Identification of patients at high risk for development of SPT is an important part of research for cancer management. This study was designed keeping this aspect in mind and utilizing the increased expression of p53 as an indicator of existence of altered fields in mirror image biopsies of OSCC patients. DESIGN: Forty clinically diagnosed oral cancer patients were included in the study. Biopsy tissue samples from clinically diagnosed oral cancer patients (Group A) and the mirror image, clinically normal looking mucosa at corresponding contralateral anatomical site (Group B) were studied for histopathological evaluation and p53 immunoexpression. RESULTS: Tissue alterations were observed in Groups A and B. There was statistically significant (chi-square value - 126.6, p=0.0001) difference in grades of epithelial dysplasia and p53 immunoexpression in Group B. Spearman's Rank Correlation Coefficient shows non-significant positive correlation between epithelial dysplasia and p53 (r=0.28, p=0.05) in Group B. CONCLUSIONS: Evidence of presence of field cancerization, evaluated by histopathological alterations and enhanced p53 expression was observed in mirror image biopsies of OSCC patients. This could predict the altered state of oral mucosa secondary to carcinogen exposure. The realization of a genetically altered field as a cancer risk factor provides a new paradigm. It would be prudent to keep these patients under close observation and to advice them chemotherapeutic regimes.