Clinical Outcome and Clinicopathological Prognostic Factors in Adenoid Cystic Carcinoma of the Head and Neck

We retrospectively reviewed the records of the 30 patients with adenoid cystic carcinoma of the head and neck (ACCHN) who had undergone initial treatment in the Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine between 1988 and 2007. The primary tumor site was the parotid gland in 10 patients and the submandibular gland in 4 patients, which account for about a half of the subjects. Thirty patients underwent surgical resection with curative intent as the primary treatment, of which 10 patients had post-operative radiotherapy. The 5-and 10-year disease-specific survival (DSS) was 73.9% and 62.4%, respectively, whereas the 5-and 10-year disease-free survival (DFS) was 64.3% and 59.7%, respectively. A univariate analysis revealed that DSS was significantly correlated with perineural invasion (p = 0.010) and lymphatic invasion (p = 0.036), while DFS was significantly correlated with higher T-stage (p = 0.044), a positive surgical margin (p = 0.012) and perineural invasion (p = 0.019). A multivariate analysis demonstrated that perineural invasion (p = 0.034, risk ratio = 9.530) was the independent prognostic factor for DSS, whereas for DFS it was a positive surgical margin (p = 0.038, risk ratio = 8.897). The histological grade classification, defined specifically for ACC, showed no correlation with the survival. Extended resection with wider margin and additional resection in cases with positive margin may improve treatment results, however, surgical resection alone can prevent neither the development of local recurrence mainly attributed to undetectable perineural invasion, nor that of delayed distant metastasis. Therefore, the roles of adjuvant radiotherapy and effective systemic therapies are also significant in ACCHN, although a reliable regimen for the latter has not yet been established. Development of a personalized strategy for the adjuvant therapy, which should be based on the accurate prediction of the long-term prognosis in combination with dependable molecular biomarkers, would be indispensable in the future to improve the clinical outcome of the patients with ACCHN.