Clinicopathologic predictors and impact of distant metastasis from adenoid cystic carcinoma of the head and neck

Background: Adenoid cystic carcinoma (ACC) is a unique tumor characterized by frequent and delayed distant metastasis (DM) with uncommon regional lymph node metastasis. Objectives: To evaluate the factors affecting DM of ACC and survival after appearance of DM. Design: A retrospective analysis of 94 cases of ACC from 1979 through 2001. Setting: Academic tertiary referral center. Results: Distant metastasis of ACC occurred in 46 patients and developed more frequently in patients with tumors of the solid histologic subtype than in patients with tubular or cribriform subtypes. Distant metastasis occurred less frequently in the minor salivary glands of the sinonasal tract than in major salivary glands or in other minor salivary glands, and development of DM was not affected by tumor stage. Disease-specific 5- and 10-year survival rates were 88% and 72% for patients without DM, respectively, and 76% and 48% for those with DM (P = .02). Regarding the site of DM and its impact on outcomes, 30 patients had lung metastasis alone; 5 patients, bone metastasis alone; and 6 patients developed both lung and bone metastasis. Median survival times after appearance of DM among patients with isolated lung metastases and those with bone metastases with or without lung involvement were 54 and 21 months, respectively (P = .04). Conclusions: Development of DM in ACC can be predicted by solid histologic subtype and major salivary gland or oral/pharyngeal rather than sinonasal primary site. Those patients with bone involvement with or without lung metastases had worse outcomes than those with pulmonary metastasis only.