Adenoid cystic carcinoma of the head and neck: a single-center analysis of 105 consecutive cases over a 30-year period

Background
Adenoid cystic carcinoma is a rare salivary gland malignancy with a poor disease free survival due to frequent distant metastases and late local recurrences. Previous single-center reports on outcome mostly encompass small series. In this report a relative large series of 105 cases is analyzed, all treated at the VU University Medical Center, Amsterdam, The Netherlands over a 30-year period in which treatment strategies remained unchanged.

Methods
All cases of ACC of the head and neck between 1979 and 2009 at our institution were analyzed through a medical chart review. Recurrence patterns and possible prognostic factors (T-stage, N-status, age, gender, type of salivary gland involved, histological grade, surgical margins, perineural invasion (PNI) and postoperative radiotherapy (RT)) were analyzed.

Results
One-hundred and five cases of ACC of the head and neck were identified. Five-, ten- and twenty-year survival rates for overall survival were 68%, 52% and 28%, respectively. T-stage, N-status, surgical margins, histological subtype and age were highly significant predictors for survival. PNI was not a negative prognosticator.

Conclusions
T-stage, N-status, surgical margins, histological grade and age are the main predictors of survival-outcome in ACC of the head and neck. Distant metastasis frequently develop, mainly in the first 5 years post treatment. Local recurrences often develop even later on, warranting long term follow up of patients treated for ACC. Grade III ACC should be considered a specific entity within the group of ACC due to its typical aggressive biological behavior and relatively poor outcome, implicating the need for an improved adjuvant treatment.