Incidence of Carcinoma of the Major Salivary Glands According to the WHO Classification, 1992 to 2006: A Population-Based Study in the United States

Background: Carcinomas of the major salivary glands (M-SGC) comprise a morphologically diverse group of rare tumors of largely unknown cause. To gain insight into etiology, we evaluated incidence of M-SGC using the WHO classification schema (WHO-2005). Methods: We calculated age-adjusted incidence rates (IR) and IR ratios (IRR) for M-SGC diagnosed between 1992 and 2006 in the Surveillance, Epidemiology and End Results Program. Results: Overall, 6,391 M-SGC (IR, 11.95/1,000,000 person-years) were diagnosed during 1992 to 2006. Nearly 85% of cases (n = 5,370; IR, 10.00) were encompassed within WHO-2005, and among these, males had higher IRs than females [IRR, 1.51; 95% confidence interval (95% CI), 1.43-1.60]. Squamous cell (IR, 3.44) and mucoepidermoid (IR, 3.23) carcinomas occurred most frequently among males, whereas mucoepidermoid (IR, 2.67), acinic cell (IR, 1.57), and adenoid cystic (IR, 1.40) carcinomas were most common among females. Mucoepidermoid, acinic cell, and adenoid cystic carcinomas predominated in females through age similar to 50 years; thereafter, IRs of acinic cell and adenoid cystic carcinomas were nearly equal among females and males, whereas IRs of mucclepidermoid carcinoma among males exceeded IRs among females (IRR, 1.57; 95% CI, 1.38-1.78). Except for mucoepidermoid and adenoid cystic carcinomas, which occurred equally among all races, other subtypes had significantly lower incidence among Blacks and Asians/Pacific Islanders than among Whites. Adenoid cystic carcinoma occurred equally in the submandibular and parotid glands, and other M-SGC histologic subtypes evaluated had 77% to 98% lower IRS in the submandibular gland. Overall M-SGC IRs remained stable during 1992 to 2006. Conclusion: Distinct incidence patterns according to histologic subtype suggest that M-SGC are a diverse group of neoplasms characterized by etiologic and/or biological heterogeneity with varying susceptibility by gender and race. (Cancer Epidemiol Biomarkers Prev 2009;18(11):2899-906)