Primary Salivary Gland–Type Lung Cancer: Clinicopathological Analysis of 88 Cases from China

Salivary gland–type cancers are rare lung neoplasms involving mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ACC), and epithelial–myoepithelial carcinoma (EMC). Their behavior and prognostic features are not clearly defined because of their low incidence. We retrospectively analyzed the clinicopathologic profiles of these tumors in a large series. Eighty-eight patients confirmed as having primary salivary gland–type lung cancer between May 2001 and January 2013 were included from the archives of two thoracic oncology center institutions in China and retrospectively evaluated. Of the total 88 patients, 69 were MEC, 12 ACC, and seven EMC. Overall survival (OS) at 3, 5, and 10 years was 91.3%, 86%, and 80.6% in all cases, respectively, and disease-free survival (DFS) was 90.1%, 78.6%, and 55%, respectively. No significant difference was found among MEC, ACC, and EMC groups regarding OS (p = 0.518) and DFS (p = 0.082). Tumor-node-metastasis stage, lymph node involvement, intrathoracic invasion, and margin status were found to be related with OS (p = 0.000, 0.029, 0.000, 0.004) and DFS (p = 0.018, 0.042, 0.002, 0.002). Intrathoracic invasion was an independent predictor for OS (hazard ratio [HR], 1.129; p = 0.039) and DFS (HR, 1.071; p = 0.011). For patients with MEC, pathological grade also was an independent predictor of OS (HR, 0.045; p = 0.006) and DFS (HR, 0.067; p = 0.001). Salivary gland–type lung cancers are a group of low-aggressive entities with higher tendency to recurrence/metastasis. Intensive clinical, radiological, and pathological examinations are essential to estimation of the risk stratification and management.