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 d escription of the incidence patterns of tonsillar SCC in the United States. Methods: Population-based incidence data from the Connecticut Tumor Registr y (period 1945-1994) and from the SEER program (period 1973-1995) were used to calculate age-standardized (US 1970) and age-specific incidence rates a nd confidence intervals (CIs). Linear regression was used to evaluate trend s. Results: The incidence of tonsillar SCC increased fourfold among white wome n in Connecticut during 1945-1994 but remained rather constant in white men . During 1973-1995, incidence rates per million person-years were considera bly 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 exp erienced significant annual increases in tonsillar SCC incidence during 197 3-1995 (2.7% in blacks and 1.9% in whites). No similar increases occurred f or 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 pra ctices alone. Changes in environmental risk factors, including changes in s moking patterns and an increase in oral human papillomavirus infections, ma y have contributed.