Keratinizing-type squamous cell carcinoma of the oropharynx: p16 overexpression is associated with positive high-risk HPV status and improved survival.

It is well established that nonkeratinizing squamous cell carcinoma (SCC) of the oropharynx is causally related to transcriptionally active human papillomavirus (HPV) and has better survival as compared with carcinomas with a keratinizing phenotype (KSCC). Although the great majority of KSCCs are unrelated to HPV, transcriptionally active HPV is detected in a minority of oropharyngeal cases. To date, it has not been established whether the HPV status in KSCC also confers a survival advantage as it does in HPV-related nonkeratinizing SCC. This study compares clinical outcomes between patients with HPV-positive versus HPV-negative oropharyngeal KSCC. Among a total of 54 cases, 7 (13%) were diffusely and strongly positive for p16. HPV E6/E7 RNA was positive in 5 of the 6 (83%) p16-positive cases that were tested and in only 1 of the 47 (2%) p16-negative cases. Only 1 of the 7 (14%) p16-positive patients developed disease recurrence and died in the follow-up period. Kaplan-Meier survival analysis showed significantly better overall and disease-specific survival in the p16-positive than in the p16-negative patients (P=0.01 and 0.046, respectively). These data, although with relatively small patient numbers, suggest that HPV-related SCC in the oropharynx is associated with highly favorable outcomes, regardless of the keratinizing or nonkeratinizing phenotype.