Primary salivary gland-type lung cancer: clinicopathological analysis of 88 cases from China.

INTRODUCTION: 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.

METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.