Investigation of predictive and prognostic relationships of EGFR mutations and P53 tissue markers in head and neck mucousal tumors

Aim: Head and neck cancers are the malignancies which originates from paranasal sinuses, nasal and oral cavity, pharynx, and larynx. Head and neck cancers accounts for approximately 5% of all cancers, and 60% of patients diagnosed with locally advanced stage during initial diagnosis. Although, the local treatment is a proper management for 60-95% of early stages, the surgery, chemotherapy and radiotherapy combination may be required for later stages. Due to high treatment resistance and high local recurrence and distant metastasis rates, prognostic factors should be determined in the head and neck cancer treatment. In this study, we aimed that the investigation of prognostic effects of EGFR gene mutations (exon18-19-20 and 21) and P53 protein expression levels in tumoral tissues as a predictive biomarkers in locally advanced stage and recurrent/metastatic advanced stage head and neck mucousal tumors. Materials and Methods: The study included 56 patients who admitted to Çukurova University Medical Faculty Adult Oncology Department with diagnosed and treated for locally advanced and recurrent/metastatic head and neck squamous cell ca between the years of 2007-2015. The EGFR mutations (exon 18, exon 19, exon20, and exon 21) detected by Real Time PCR method and P53 expression levels from paraffin blocked tissues were assessed by a pathologist at Cukurova University Faculty of Medicine. Patients were divided according to stages as locally advanced (stage III), advanced stage (stage IVA-IVB) and metastatic (stage IVC). EGFR (exon 18,19,20 and 21) mutations and p53 expression levels were compared with prognostic factors, histopathologic markers and clinical outcomes. Results: When evaluating of EGFR mutations (exon 18-19-20-21) analyzed by Real Time PCR, all patients (n=56) had no detectable mutations and therefore, the statistical evaluation could not be made. While there were no statistical relationship between P53 protien expression levels, and survival, recurrence, tumor stage, tumor location, differantiation grade and lymph node positivity (p=0.384, p=0.774, p=0.18, p=0.343, p=0.782, p=0.229),a significant association was found between p53 protein expression levels and metastasis (p=0.048). It is observed that there was an increased rate of metastasis while the p53 protein expression level increased in tumoral cells. Additionally, in cigarette smokers, predominantly p53 protein expression level has been identified as > 20% and it was observed that statistically significant (p=0.034). Conclusions: Since the EGFR (exon 18, 19, 20 and 21) mutations could not be determined in all patients, this negative result add an important contribution to the literature. Because of there were no statistical relationship between P53 protien expression levels, and survival, recurrence, tumor stage, tumor location, differantiation grade and lymph node positivity, advanced statistical evaluations may be done with larger patient cohort studies. Keywords: Head and neck cancers, EGFR mutations, P53