Outcomes and prognostic factors for parotid acinic cell Carcinoma: A National Cancer Database study of 2362 cases.

OBJECTIVES: To evaluate the demographics, clinical features, survival outcomes, and prognostic indicators of patients with acinic cell carcinoma (ACC) of the parotid gland with emphasis on the roles of grade, tumor size, and nodal status in survival.

MATERIALS AND METHODS: A retrospective analysis of cases diagnosed between 2004 and 2012 from the National Cancer Database was performed. Multivariable logistic regression was used to determine factors associated with survival.

RESULTS: 2362 cases were identified. Most patients were females (61.3%) and Caucasian (85.4%) with a median age of 54 years (range, 18-90 years). Most tumors were <3 cm in size (75.8%). Regional metastases and high-grade histology were rare (8.2%, 5.1%). All patients received surgery as primary treatment with 42.7% of patients receiving adjuvant radiation therapy or chemoradiotherapy. 5 year overall survival was 88.6%. On multivariable analysis, age >70 years (hazard ratio [HR]: 10.05, 95% confidence interval [CI]: 5.64-17.91), high-grade (HR: 5.30, 95% CI: 3.39-8.29), tumor size of 3 to 6 cm (HR: 1.53, 95% CI: 1.10-2.12), tumor size >6 cm (HR: 2.98, 95% CI: 1.681-5.289), pN2+ (HR: 3.14, 95% CI: 2.10-4.69), T4 (HR: 2.89, 95% CI: 1.74-4.80) were significant prognosticators.

CONCLUSION: Although patients with ACC generally are considered to have a favorable prognosis, an aggressive subgroup with poor outcomes was identified. This group is characterized by high-grade, advanced T classification, tumors larger than 3 cm, with regional metastases and age greater than 70 years. Histologic grade is a substantially stronger predictor of survival than T and N classifications.