The Evolving Epidemiology of Oral Cavity and Oropharyngeal Cancers

In 1988, Blot and colleagues reported results from a U.S. case-control study of oral cavity or pharyngeal (oropharyngeal and hypopharyngeal) cancers, with results showing independent associations of smoking and alcohol with increased risk, multiplicative interaction effects between smoking and alcohol, and that nearly three-quarters of these cancers are attributable to smoking and alcohol. The report by Blot and colleagues represents a landmark in oropharyngeal cancer epidemiology. This study, the largest at the time, introduced several novel concepts in oropharyngeal cancer epidemiology that remain relevant today-etiologic heterogeneity, statistical interaction effects, adjusted attributable fractions, and disparities by sex and race/ethnicity. Perhaps the most significant recognition in the field since 1988 is the etiologic association of human papillomavirus (HPV, primarily HPV16) with cancers arising in the oropharynx. Today, more than 80% of oropharyngeal cancers in the United States are caused by HPV while only approximately 3% of oral cavity cancers are caused by HPV. This etiologic heterogeneity across head and cancer subsites revealed by HPV is manifest at the genetic/genomic, epidemiologic, and clinical levels. Tobacco and alcohol remain the major etiologic factors for oral cavity cancers while HPV is the major cause of oropharyngeal cancers. Thus, tobacco and alcohol control and prophylactic HPV vaccination remain the most promising prevention tools for oral cavity and oropharyngeal cancers at this time. Importantly, the ever-emerging alternative tobacco products, such as smokeless tobacco/snus, hookah and water pipes, e-cigarettes, flavored cigars and cigarillos, and oral dissolvable products, represent a key public health concern and the carcinogenic effects of these products remains an active area of investigation. See related article by Blot and colleagues, Cancer Res 1988;48:3282-7.