Lung metastasis in adenoid cystic carcinoma of the head and neck

Background Distant metastasis of adenoid cystic carcinoma (ACC) is most commonly identified in the lung, but risk factors are still on debate. Methods Risk factors for lung metastasis were evaluated by using Cox proportional hazards model and Kaplan-Meier curves. Results Of 112 patients, 48% had distant metastasis; 94.4% of whom had lung metastasis. Univariable analysis revealed sublingual or minor salivary gland, tumor size >= 2.5 cm, and perineural invasion as risk factors (hazard ratio [HR]: 1.99 [1.02-3.91], 2.57 [1.19-5.58], and 2.46 [1.28-4.74], respectively), whereas size, perineural invasion, and local recurrence were risk factors in multivariable analysis (HR: 2.29 [1.05-4.96], 2.32 [1.09-4.96], and 2.68 [1.24-5.79], respectively). Conclusion Sublingual gland or minor salivary glands ACC has a higher risk of lung metastasis. If the site is not considered, the following factors increased the risk of lung metastasis; (a) size >= 2.5 cm, (b) perineural invasion, and (c) local recurrence.