Bidirectional association of anogenital and oral cavity/pharyngeal carcinomas in men.

OBJECTIVE To test the hypothesis of a bidirectional association of anogenital and oral cavity/pharyngeal human papillomavirus (HPV)-associated cancers in men. DESIGN Population-based epidemiological study using the Surveillance, Epidemiology, and End Results cancer database. SETTING Population-based cancer study involving patients receiving care in the United States. PARTICIPANTS The study included 47,308 men 20 years and older with an index oral cavity/pharyngeal or anogenital cancer. MAIN OUTCOME MEASURE Second primary HPV-associated cancers (anogenital or oral cavity/pharyngeal) or HPV-unrelated cancers (prostate, bladder, or colon). RESULTS The standardized incidence ratio (SIR) was elevated for both anogenital cancer following oral cavity/pharyngeal cancer (SIR, 1.9; 95% confidence interval [CI], 1.2-2.7) and oral cavity/pharyngeal cancer following anogenital cancer (SIR, 3.0; 95% CI, 2.1-4.2). The increase in SIR was most pronounced for tonsillar cancer following anal cancer (SIR, 8.4; 95% CI, 2.7-19.6). The risk of second primary HPV-associated cancers did not vary significantly by age, race, year of diagnosis, or geographic location but was greater among never-married men, particularly for anal cancer following oral cavity/pharyngeal cancer (SIR, 6.5; 95% CI,1.8-16.7 in never-married men, but SIR, 1.6; 95% CI, 0.7-3.1 in ever-married men) and for tonsillar cancer following anogenital cancer (SIR, 13.0; 95% CI, 3.5-33.2 in never-married men, but SIR, 3.8; 95% CI, 1.0-9.7 in ever-married men). Other than a slightly increased risk of tongue cancer following colon cancer (SIR, 1.3; 95% CI, 1.1-1.6), there was no increased risk of oral cavity/pharyngeal or anogenital cancer following HPV-unrelated cancers or vice versa. CONCLUSION The association between index and second primary anogenital and oral cavity/pharyngeal cancers, strongest in never-married men, supports the influence of sexual behavior on the risk of HPV-associated head and neck cancers.