Evaluation of Molecular Positive Margins Using Surrogate P53 and Retinoblastoma Protein Expression and Correlation with Surgical Outcomes in Oral Squamous Cell Carcinoma

Abstract

BACKGROUND p53 mutation and Rb over-expression have been extensively studied in oral squamous cell carcinoma (OSCC) but their clinical relevance with respect to excision margins is still controversial. The purpose of the study was to determine the expression of molecular markers (p53& Rb) for predicting early locoregional recurrence in oral cancer. METHODS Histopathological specimens of 93 patients of oral cavity squamous cell carcinoma were subjected to p53 mutation and Rb protein testing in tumour and at the closest negative margin on H &E using immunohistochemistry. The expression of p53 and Rb in tumour tissue and at excision margin was correlated with clinicopathologic parameters recurrence and survival over a 2 year follow up period. RESULTS p53 mutation expression in tumour tissue was associated with increased recurrence (22.5 % versus 11.3 % P = 0.13) and mortality (17.5 % versus 5.6 % P = 0.056). p53 expression at margins is also associated with higher recurrence and mortality. Rb overexpression in tumour tissue is not significantly associated with recurrence (15 % and 16.4 %). Rb overexpression at margins had higher recurrence (40 %; P = 0.627) and higher mortality (60 %) in comparison to Rb negative cases (16.4 %versus 6.8 % respectively). CONCLUSIONS Clinical and routine histopathological assessments of margins remain the standard method of prognosticating and planning adjuvant treatment. Determination of molecular positive margins using p53 & Rb in oral cancer may aid in identifying patients at high risk of development of recurrence despite negative pathological margins. KEYWORDS Rb, Margin, P53, Recurrence.