Two types of squamous cell carcinoma of the palatine tonsil characterized by distinct etiology, molecular features and outcome

To determine whether human papillomaviruses (HPV) positive tonsillar squamous cell carcinoma (SCC) represent a specific entity, we studied the prevalence of HPV association and of tobacco/alcohol exposure in a series of 52 cases of tonsillar SCC cases. p53, p16, and pRb levels, deregulated by viral oncoproteins were assessed. Forty patients reported tobacco/alcohol exposure, 10 reported no exposure. HPV DNA was found in 32/52 (62%) cases, (HPV16 genotype in 27). All patients with no history of tobacco-alcohol exposure presented HPV positive tumor (p=0.0008). A strong correlation was observed between positive HPV status, decrease in pRB and increase in p16 expression level. 5 year overall survival rate was higher in HPV16 positive patients than in HPV negative (71% versus 36%; p=0.023). HPV status remained a significant prognostic factor in multivariate analysis. Tonsillar SCC can thus be divided in HPV positive and negative subgroups with different oncogenesis and response to treatment.