Salivary gland carcinoma in Denmark: a national update and follow-up on incidence, histology, and outcome

Purpose: Salivary gland carcinoma is a rare disease and studies on epidemiology and outcome require data collection over many years. The aim of this study is to present an update of incidence rates, anatomical sites, histological subtypes, and survival rates based on the Danish national cohort of salivary gland carcinoma patients.

Methods: Data from all Danish patients with salivary gland carcinoma diagnosed from 1990 to 2015 (n = 1601) were included and analyzed following histological reevaluation and reclassification. Overall, disease-specific, and recurrence-free survival were evaluated. Prognostic factors were analyzed with multivariate Cox Hazard Regression.

Results: The study population consisted of 769 men and 832 women, median age 62 years (range 6-102). The most frequent anatomic site was the parotid gland (51.8%). Adenoid cystic carcinoma was the most common subtype (24.7%). The majority had tumor classification T1/T2 (65.3%). The mean crude incidence was 1.2/100.000/year with an increase of 1.5% per year. There was no increase in age-adjusted incidence. The 5-, 10-, and 20-year survival rates were for overall survival 68, 52, and 35%, for disease-specific survival, 77, 69, and 64%, and for recurrence-free survival, 75, 64, and 51%, respectively. Age, high-grade histological subtype, advanced T-classification, cervical lymph node metastases, vascular invasion, and involved surgical margins had significantly negative impact on survival rates.

Conclusion: The age-adjusted incidence has been stable for a period of 26 years. Multivariate analysis confirmed that histological grade, advanced stage, involved surgical margins and vascular invasion are independent negative prognostic factors. Survival rates were stationary compared to earlier reports.