Incidence trends for human papillomavirus-related (HPV-R) and unrelated (HPV-U) head and neck squamous cell carcinomas (HNSCC) in the United States (US)

Abstract

6001 Background: HNSCC are etiologically heterogeneous, with one subset primarily attributable to HPV and another to tobacco and alcohol. Methods: Data from SEER9 program registries were used to investigate the potential influence of HPV on incidence and survival of HNSCC in the US from 1973–2003. HNSCCs (N=58,158) were classified by anatomic site as potentially HPV-R (base of tongue; tonsil; oropharynx; N=16,712) or HPV-U (lip; tongue; gum; floor of mouth; palate; other mouth; hypopharynx; ill-defined sites of lip, oral cavity, and pharynx; N=41,446). Joinpoint regression was used to assess incidence trends and life-table methods were used to compare survival for HPV-R and HPV-U HNSCCs. Results: For HPV-R HNSCCs, age-adjusted incidence increased significantly from 1973–2003 (annual percent change [APC] = 0.65), particularly among males (APC=1.02), whites (APC=0.89), and younger ages (APCs for 30–39 = 1.46; 40- 49=1.92; 50–59=0.61, and =60= -0.66). By contrast, HPV-U HNSCC incidence was stable from 1973–1983 and then decreased significantly from 1983–2003 (APC= -2.42). Mean age at diagnosis was younger for HPV-R HNSCC than HPV-U (61.1 vs. 64.5 years; p<0.001), and from 1973- 2003, decreased significantly for HPV-R, but increased for HPV-U. Improvements in overall survival (OS) were observed for HPV-R (all stages) and HPV-U (regional and distant) HNSCC treated by radiotherapy (RT) from 1973–2003, but were more marked for HPV-R HNSCC, e.g. absolute increase in two-year OS for regional disease of 24.4% (vs. 5.8% for HPV-U). OS for HPV-R (local and regional) was significantly better than HPV-U HNSCC if treated by RT, but worse if not so treated. Conclusions: The proportion of HNSCC that is potentially HPV- R increased in the US from 1973–2003, particularly among recent birth cohorts, perhaps due to changing sexual and smoking behaviors. Recent improvements in locoregional control with RT-based therapy may be due in part to a gradual shift in the etiology of the underlying disease. No significant financial relationships to disclose.