Contribution of demographic and behavioral factors on the changing incidence rates of oropharyngeal and oral cavity cancers in northern California

Abstract

Background: It is unknown to what extent patient demographics, smoking, and alcohol use have contributed to changes in oropharyngeal and oral cavity cancer incidence rates.

Methods: We performed a cohort study of Kaiser Permanente health plan members, ages 20 to 89, for years 1995-2010 (n = 2.2 million annual members). Poisson Regression models estimated calendar trends in cancer rates both adjusted for and stratified by age, sex, smoking, and alcohol abuse history.

Results: We identified 1,383 human papillomavirus (HPV)-related and 1,344 HPV-unrelated oral cavity and oropharyngeal cancer cases. With adjustment for age and sex, HPV-related cancer incidence rates increased 3.8% per year (P < 0.001) between 1995 and 2010, whereas rates for HPV-unrelated cancers decreased 2.4% per year (P < 0.001). For years 2007 to 2010, with additional adjustment for smoking and alcohol abuse, results were nonsignificant, but similar in magnitude. The increasing rates for HPV-related cancers were more prominent among nonsmokers (+14.5%) compared with smokers (-2.5%; P-interaction = 0.058). The decreased rates for HPV-unrelated sites were more prominent among those ≥ 60 years (-11.0%) compared with those <60 years (+16.8%; P-interaction = 0.006), among smokers (-9.7%) compared with nonsmokers (+8.4%; P-interaction = 0.055), and among those with an alcohol abuse history (-20.4%) compared with those without a history (+5.8%; P-interaction = 0.009).

Conclusions: The observed increasing HPV-related cancer rates are most evident among nonsmokers, whereas the decreasing HPV-unrelated cancer rates are least evident among younger individuals, nonsmokers, and those without an alcohol abuse history.

Impact: Continued vigilance for oropharyngeal and oral cavity cancer is warranted, including among those without traditional risk factors such as smoking and alcohol abuse.