Changing patterns of tonsillar squamous cell carcinoma in the United States.

OBJECTIVE: Tonsillar squamous cell carcinoma (SCC) may differ etiologically from other oral cancers. The aim of this study was to provide a detailed description of the incidence patterns of tonsillar SCC in the United States.
METHODS: Population-based incidence data from the Connecticut Tumor Registry (period 1945-1994) and from the SEER program (period 1973-1995) were used to calculate age-standardized (US 1970) and age-specific incidence rates and confidence intervals (CIs). Linear regression was used to evaluate trends.
RESULTS: The incidence of tonsillar SCC increased fourfold among white women in Connecticut during 1945-1994 but remained rather constant in white men. During 1973-1995, incidence rates per million person-years were considerably higher in blacks (31.6; 95% CI: 29.0-34.4 in men, and 9.6; 95% CI: 8.3-10.9 in women) than whites (14.8; 95% CI: 14.3 15.3 in men, and 6.1; 95% CI: 5.8-6.4 in women). Men, but not women, who were younger than 60 years experienced significant annual increases in tonsillar SCC incidence during 1973-1995 (2.7% in blacks and 1.9% in whites). No similar increases occurred for oral SCC at non-tonsillar sites.
CONCLUSION: Incidence rates of tonsillar SCC vary considerably by sex, race and time in a way that cannot be explained by changes in tonsillectomy practices alone. Changes in environmental risk factors, including changes in smoking patterns and an increase in oral human papillomavirus infections, may have contributed.