Outcomes and prognostic variables in adenoid cystic carcinoma of the head and neck: a recent experience.

Purpose: To analyze the recent experience of patients with adenoid cystic carcinoma treated with radiation therapy at Memorial Sloan-Kettering Cancer Center.
Methods and Materials: From 1990 to 2004, a total of 59 patients with a diagnosis of primary adenoid cystic carcinoma of the head and neck received radiation therapy at our institution. The subsite distribution was oral cavity, 28% (n = 17); paranasal sinuses, 22% (n = 13); parotid, 14% (n = 8); submandibular, 14% (n = 8); oropharynx, 10% (n = 6); sublingual, 3% (n = 2); nasopharynx, 3% (n = 2); and other, 5% (n = 3). T Stage distribution was T1, 34% (n = 20); T2, 19% (n = 11); T3, 14% (n = 8); and T4, 34% (n = 20). Twenty-nine percent of patients (n = 17) were treated with intensity-modulated radiation therapy; 25% (n =15), with three-dimensional conformal therapy, and the remainder, with conventional techniques. Ninety percent (n = 53) of patients received treatment including the base of skull.
Results: Median follow-up for surviving patients was 5.9 years. Five-year and 10-year rates of local control and distant metastases-free survival were 91%/81% and 81%/49%, respectively. Five-year and 10-year rates of disease-free and overall survival were 76%/40% and 87%/65%, respectively. On univariate analysis, stage T4 (p = 0.004) and gross/clinical nerve involvement (p = 0.002) were associated with decreased progression free survival, whereas stage T4 and lymph node involvement were associated with decreased overall survival (p = 0.046 and p < 0.001, respectively).
Conclusions: Radiation therapy in combination with surgery produces excellent rates of local control, although distant metastases account for a high proportion of failures. Routine treatment to the base of skull reduces the significance of histologic perineural invasion, but major nerve involvement remains an adverse prognostic factor.