What cancers explain the growing rural-urban gap in human papillomavirus-associated cancer incidence?

Purpose

Human papillomavirus (HPV) can cause cancers of the genital system, anus/rectum, and oropharynx. Prior research showed that HPV-associated cancer incidence was rising faster in nonmetro than in metro populations. Our study identified which cancers contributed to the widening disparity.

Methods

Representing ∼93% of all cancers in the United States, we analyzed data from the North American Association of Central Cancer Registries (2000-2019). Restricting the analysis to HPV-associated cancers, we compared 5-year average age-adjusted incidence rates (per 100,000 population) for nonmetropolitan (Rural-Urban Continuum Codes 4-9) and metropolitan populations, by sex and cancer site. To quantify the rural-urban gap, we calculated rate ratios and absolute differences of incidence trends.

Results

Although incidence was similar in 2000-2004 (nonmetropolitan = 9.9; metropolitan = 9.9), incidence in 2015-2019 was significantly higher in nonmetropolitan (12.3) than metropolitan (11.1) populations. The gap was widest for cervical cancers (females) in 2015-2019 (1.0 case per 100,000) but grew the most since 2000-2004 in oropharyngeal cancers among males (+1.1 cases per 100,000). The nonmetropolitan rate ratios for females (RR = 1.15, 95% C.I. = 1.13, 1.17) and males (RR = 1.07, 95% C.I. = 1.05, 1.09) in 2015-2019 were higher than the respective RRs for all other years. Since 2000, the nonmetropolitan disparity has significantly grown for anal and cervical cancers in females, and oropharyngeal cancers in both sexes.

Discussion

Although preventable, nonmetropolitan Americans have shouldered a growing burden of HPV-associated cancers. To address these cervical, anal, and oropharyngeal cancer disparities, it is imperative that HPV vaccination programs are effectively implemented at scale.