Growth of the Epidemic of Human Papillomavirus-Related Oropharyngeal Carcinomas in Whites in Selected US Metropolitan and Nonmetropolitan Counties, 1992-2013.

BACKGROUND: Age-standardized incidence rates (ASIRs) for US non-Hispanic whites (NHWs) have been increasing since 1999 for squamous cell carcinomas (SCC) at oropharyngeal (OP) anatomic sites strongly associated with human papillomavirus (HPV), as also reported from certain European countries. ASIRs declined slightly, however, from 2000–2006 to 2007–2012 in Stockholm County, Sweden (an urban area) for SCC of the tonsil (TSCC) but not base of tongue (BTSCC). For the United States, this study examined the growth of the epidemic of these cancers in 1992–2013. METHODS: Using join-point regression, trends were examined in ASIRs for BTSCC and TSCC for NHWs in US metropolitan vs nonmetropolitan counties included in a unique Surveillance, Epidemiology, and End Results (SEER) program database covering 1992–2013 (11 registries). Representativeness of recent trends was assessed using a larger SEER database (17 registries) covering only 2000–2013. RESULTS: ASIRs for NHWs were lower for nonmetropolitan vs metropolitan counties in 1992–1996 but rapidly increased and converged over time (especially using SEER-17). There was no decline in rates for TSCC in metropolitan counties, but for BTSCC, the increase was smaller in recent vs earlier years. Reporting delay of cases diagnosed in recent years was low in both groups of counties. CONCLUSIONS: Findings indicate the need for ongoing surveillance including additional US registries, and determining if rates in nonmetropolitan counties will surpass those in metropolitan counties. The rapid rise in rates in SEER nonmetropolitan counties also suggests the need for similar surveillance in countries with larger rural populations.