Abstract A36: Clinical and molecular characterization of oropharynx squamous cell carcinoma samples

Abstract

Abstract Background: Oropharynx squamous cell carcinomas (OPSCC) associated with high-risk human papilloma virus (HR-HPV) infection represent a distinct clinical and epidemiologic entity, with differences in clinical presentation and treatment outcome when compared to tobacco-associated tumors. Objective: The aim of this study was to identify clinical and molecular factors that can differentiate OPSCC patients into subgroups according to their outcome. Materials and Methods: Twenty-five surgically treated OPSCC samples were included in this study. p16 protein expression was used as a surrogate marker for HR-HPV. The methylation status of 5 genes was evaluated by quantitative methylation-specific PCR (qMSP). Exons 4-8 of the P53 gene were evaluated by Sanger sequencing and p53 protein expression was evaluated by immunohistochemistry (clone DO-7). Results: The majority of patients (88%) were male, had advanced disease (80%), and were tobacco users (88%). Twenty percent of the cases were HR-HPV positive and 62.5% presented deleterious P53 mutations, which was moderately concordant with strong p53 protein expression (Kappa value = 0.467; p = 0.022). CCNA1, CDH8, DAPK, PCDH10, and TIMP3 promoter hypermethylation was observed in 16-36%, of the OPSCC evaluated. DAPK hypermethylation was associated with HPV status (p = 0.023), while CCNA1 methylation was inversely related to p53 mutations in primary tumors (p = 0.042) and associated with a better disease-free survival (22.3% vs. 100%; p = 0.028) and overall survival (8% vs. 100%; p = 0.012). Conclusions: Even though all samples analyzed were of the oropharynx, several differences regarding molecular and clinical characteristics were identified. More cases should be evaluated in order to assess whether the differences identified are able to classify these patients according to their outcome and help in a more thorough patient management. Citation Format: Ana Carolina de Carvalho, Bruna Pereira Sorroche, Matias Eliseo Melendez, Cristina da Silva Sabato, Edenir Inez Palmero, Lidia Maria Rebolho Batista Arantes, Cristovam Scapulatempo Neto, André Lopes Carvalho. Clinical and molecular characterization of oropharynx squamous cell carcinoma samples [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A36.