Demographic trends and disease-specific survival in salivary acinic cell carcinoma: an analysis of 1129 cases.

OBJECTIVE/HYPOTHESIS: Acinic cell carcinoma (AciCC) is a rare salivary gland malignancy that most commonly arises in the parotid gland. Characteristics of AciCC are slow growth and a long clinical course. As a rare tumor, population-based studies are limited. We analyzed the incidence and survival for AciCC using a national population-based database. STUDY DESIGN: Retrospective analysis. METHODS: The United States National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry was utilized to calculate incidence and disease-specific survival trends for AciCC between 1973 and 2009. Patient data were stratified according to age, gender, race, grade, and extent of disease. Incidence trends were studied across the last 30 years and long-term disease-specific survival outcomes were compared across the different demographic parameters. RESULTS: A total of 1,129 cases of AciCC were identified, comprising of 672 (59.52%) females. Incidence trend analysis revealed significant changes in yearly incidence rates from 1973 to 2009 for male gender and white and "others" races. Overall 5-year survival was 97.15%, 10-year survival was 93.81%, and 20-year survival was 89.74%. Significant differences in survival outcomes were noted for extent of disease. Patients exhibiting distant metastasis displayed the worse long-term prognosis at 21.99% 20-year disease-specific survival. Hazard ratios demonstrated a significant increase in mortality in patients with poorly differentiated, undifferentiated, and metastatic disease. CONCLUSION: Trends in incidence of AciCC are influenced by gender, race and age. Long-term survival of this rare malignant tumor is influenced by gender, grade, race, and extent of disease. Future studies need to be conducted to investigate these dynamic trends related to AciCC.