Frequent hepatocyte growth factor overexpression and low frequency of c-Met gene amplification in human papillomavirus-negative tonsillar squamous cell carcinoma and their prognostic significances.

Human papillomavirus (HPV) is an important prognostic factor for tonsillar squamous cell carcinoma (TSCC). HPV-positive and HPV-negative TSCCs are considered distinct in terms of prognosis and sensitivity to chemo/radiotherapy. However, to date, no study has thoroughly evaluated the individual prognostic factors for these 2 disease subgroups. Hepatocyte growth factor (HGF)-Met signaling pathway can be a predictive marker for prognosis or therapy response, especially in HPV-negative TSCC. We therefore investigated the prognostic values of HGF and c-Met expression in TSCC according to HPV status. Immunohistochemical analyses of HGF and c-Met protein expression and silver in situ hybridization of c-Met gene copy number were performed in 79 formalin-fixed, paraffin-embedded specimens. In HPV-negative TSCC, HGF overexpression, regional lymph node category, and ipsilateral cervical nodal metastasis predicted decreased overall survival (OS) (P = .017, P = .024, and P = .003, respectively). The latter 2 were also independent prognostic factors for progression-free survival (P = .023 and P = .002, respectively). In HPV-positive TSCC, heavy alcohol consumption and advanced primary tumor category were predictive of progression-free survival, whereas no independent prognostic factor for OS was identified. HGF overexpression had a significant effect on OS in HPV-negative TSCC but not in HPV-positive TSCC. HPV-negative/HGF-high expression tumors exhibited the worst survival outcomes, whereas HPV-positive/HGF-low expression tumors had the most favorable prognosis. c-Met expression and c-Met gene amplification were not associated with survival outcomes in TSCC patients. In conclusion, HGF may be a potential prognostic marker in HPV-negative TSCC, whereas c-Met exhibited limited clinical significance in TSCC.