OP026: Prognostic significance of tumor progression and human papilloma virus in advanced tonsillar cancer classified as stage IVA

Abstract

Objective In the American Joint Committee on Cancer (AJCC) TNM staging of oropharyngeal cancer, T1-4a and N0-2c tumors are classified as the same stage (IVA), but their biological behaviors may be notably different. Our aim in this study was to identify clinical factors that can explain the differences in treatment outcome and to examine the value of HPV infection as a prognostic biomarker for stage IVA tonsillar carcinomas. Study design Retrospective review. Methods Seventy-four patients with tonsillar cancer classified as stage IVA were retrospectively analyzed with respect to survival outcomes according to various clinical factors. Among those analyzed, tissue from 24 patients was tested for HPV infection using a HPV DNA chip test and immunohistochemical staining of p16 and p53. Results The disease-specific overall survival rate (OSR) between groups was not different according to various clinical factors. However, the disease-free survival rate (DFSR) was significantly lower according to the progression of local invasiveness and nodal status (p = 0.01). Furthermore, although HPV positivity and p16 expression was more often found in locally advanced tonsillar carcinomas with advanced lymph node metastasis, the 5-year OSR was better in the HPV/p16-positive tumor patients. Conclusion Even though AJCC staging system is a well-designed prognostic system showing the same OSR for all stage IVA tonsillar cancers, the DFSR may be different according to local invasiveness of the tumor and nodal status. In addition, HPV infection may be a useful biomarker for predicting treatment outcomes for stage VIA tumors.