MC13-0050 Proteomic markers in early buccal mucosa squamous cell cancers

Abstract

Background: Carcinoma of buccal mucosa is common in South Asia due to large-scale usage of chewable tobacco. However, clinically these cancers behave similar to tongue cancers, which are common in western countries. Like any other head and neck squamous cell cancers (HNSCC), their prognosis is affected by established clinical factors like nodal metastasis and T stage. Presence of regional lymph node metastasis is one of the important factors for poor clinical outcome and nodal status of the neck plays a decisive role in the choice of treatment. An assessment of the cervical lymph node metastatic status in oral cavity cancer not only helps to predict the prognosis of patients, but also helps surgeons to choose the appropriate treatment. About 70% of patients in T1 (<2 cm) and 30% in T4 primary tumour stage may not have lymphatic metastasis at the time of treatment. Similarly, even after using all the available technologies to detect lymph nodes in the neck, the rate of occult metastasis is significantly high in OSCC. Many literature reports points to several molecular markers expressed by the primary tumour in predicting its metastasising nature. It is important that these markers should be such that their use can be effectively translated into easy to implement techniques in any molecular pathology laboratory. While gene expression profiles are increasingly used for prognostication, their relative costs and time requirements make them difficult for routine use in clinical service. Proteomic markers can be detected using IHC and will be easier to use clinically. Purpose/Objective: This study aims in developing a set of markers in early buccal mucosa cancers using previously established set of proteomic markers differentially expressed in buccal mucosa cancers. Materials and Methods:We have analyzed formalin fixed paraffin embedded blocks from 90 patients with early stage (T1/T2) buccal mucosa cancers treated surgically at Tata Memorial Hospital, Mumbai. All patients were clinically node negative at the time of surgery. Tissue microarrays was prepared and the sectons stained with antibodies for 19 markers. The stained slides were graded and quantified based on the localization, extent of staining and intensity of staining. Results: Median expressions of P53 and EGFR between node negative and positive tumors were not significant. However, we observed significant differences in the expression of the following markers among node negative versus node positive tumor samples. 1. Higher expression of SFN is associated with lower risk of nodal metastasis (p 0.03), 2. Higher expression of TCTP is associated with lower risk of nodal metastasis (p 0.003). These markers along with 14-3-3-zeta also showed significant differences in expression between well differentiated tumors and others. Conclusions: Proteomic markers have potential to predict nodal metastasis in early stage buccal mucosa cancers.