Evolving disparities in the epidemiology of oral cavity and oropharyngeal cancers.

Incidence rates of head and neck cancers (HNC) associated with human papillomavirus (HPVa) infection are increasing while non-HPV-associated (non-HPVa) HNC cancer rates are decreasing. As nearly all sexually active individuals will acquire an HPV infection, it is important to understand epidemiologic trends of HNCs associated with this sexually transmitted disease. We analyzed SEER 9 (1973-2012) and 18 data (2000-2012) for HPVa HNCs (oropharynx area; OP) and non-HPVa (oral cavity area; OC). Incidence rates were examined by gender, race, rurality, geographic location, and time. Joinpoint regression analyses assessed temporal variations. From 1973 to 2012, OC incidence decreased while OP increased, with changes largely driven by males (whose OP rate increased 106.2% vs female decrease of 10.3%). Males consistently had higher rates of both cancer groups across each registry except Alaska, OP rates among blacks changed from significantly above whites to below, and trend analysis indicated significant differences in rates over time by gender, race, and geography. Analysis of SEER 18 found that rates discordantly varied by group and gender across the 18 registries, as did the male/female rate ratio with overall means of 4.7 for OP versus 1.7 for OC (only Alaska and Georgia having overlapping ranges). Our findings indicate that much of the HPVa rate increases were driven by rate increases among males and that there were changing differences in risk between genders, race, and geographic location. The epidemiology of HNCs is complex, with locally relevant factors requiring further research for elucidation of demographic disparities in incidence.