Prognostic factors affecting the clinical outcome of adenoid cystic carcinoma of the head and neck

Background: Adenoid cystic carcinoma (ACC) is an uncommon tumor, constituting approximately 10% of all head and neck tumors. Classically, ACC has been described as a tumor with indolent, but persistent and recurrent, growth and late onset of metastases, leading eventually to death. This study assessed the prognostic factors affecting the clinical outcome in patients with ACC in the head and neck region. Methods: We performed a retrospective study of 42 patients who underwent primary tumor resection or radiotherapy with curative intent and evaluated the clinical parameters, treatment and clinical outcomes. Results: Forty-two patients (18 males and 24 females with a median age of 65 years) received curative treatment. The overall 3- and 5-year survival was 87.4% and 55.3%, respectively, whereas the 3- and 5-year disease-free survival was 64.3% and 36.1%, respectively. Of the 32 patients in whom recurrence could be evaluated, 18 (56.3%) developed distant metastases, with the lung (72.2%) being the most common site. Perivascular invasion influenced metastasis to the lung with borderline significance (P = 0.053). The recurrence rate was higher (P= 0.045) in patients with high-grade tumor. The status of lymph node metastasis was significantly associated with overall survival (P= 0.030). Conclusions: High tumor grade and lymph node involvement were predictive of recurrence and overall survival, respectively. Despite aggressive treatment, it seems to be impossible to prevent the development of distant metastasis. Therefore, more research is needed to identify molecular biomarkers that predict the clinical outcome and to develop effective treatment for patients with ACC.