BACKGROUND

This study was aimed at investigating the change in the prevalence of human papillomavirus (HPV) genotypes in tonsillar squamous cell carcinoma (TSCC) and the association of the HPV genotype with the prognosis.

METHODS

This multicenter study included 175 patients with TSCC from 3 general hospitals between 1991 and 2009. HPV DNA was detected in paraffin-embedded tissues with genotyping chips. A survival analysis that considered clinicopathological factors, the HPV genotype, and the expression of p53, retinoblastoma protein, p16, and epidermal growth factor receptor (assessed with immunohistochemistry) was performed with Cox regression analysis.

RESULTS

High-risk HPV types were found in 23.4% of the cases. The prevalence of HPV-18 (10.3%) was as high as that of HPV-16 (10.3%). The proportion of high-risk HPV-positive tumors increased from 5.9% in 1991 to 31.6% in 2009. HPV-16 positivity was associated with an advanced stage and lymph node metastasis, whereas HPV-18 positivity was associated with old age and an advanced T stage. The survival analysis showed that old age and T classification were poor prognostic factors, whereas the expressions of various biomarkers were not associated with prognosis. HPV-18-positive cases had a poorer prognosis than HPV-16-positive cases and non-HPV-related TSCC cases. A multivariate analysis revealed that HPV-18 positivity, old age, and an advanced T stage were independent prognostic factors for predicting poor outcomes for patients with TSCC.

CONCLUSIONS

The proportion of HPV-positive tonsillar cancer cases has increased during the last 20 years in the Republic of Korea. The presence of HPV-18 may serve as a biomarker for a poor prognosis.