Primary salivary gland-type lung cancer: spectrum of clinical presentation, histopathologic and prognostic factors.

Background: Primary salivary-type lung cancers are rare tumors that include adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). The clinicopathologic profiles, symptoms on presentation, and long-term outcomes of patients with ACC and MEC as an overall group have not been defined recently.

Methods: In this study, the authors analyzed clinical outcome data from 62 patients who presented with a diagnosis of primary salivary-type lung cancer at the Mayo Clinic (Rochester, Minn) from 1972 to 2002.

Results: The median age at diagnosis for patients with MEC was 40 years (range, 6-78 years); and, for patients ACC, the median age at diagnosis was 54 years (range, 21-76 years). ACC was observed more frequently among women and girls. The main presenting symptom for both tumors was cough (70%), followed by dyspnea (51.7%), wheezing (38.3%), obstructive pneumonia (30%), hemoptysis (28.3%), and fever (16.7%). Tissues were available for review from all patients. Among the ACC tumors, 29 (74.4%) were cribriform, 7 (17.9%) were tubular, and 3 (7.7%) were the solid type. Most MEC tumors (65%) were intermediate grade (grade 2), and 30% were low grade (grade 1). Most salivary-type lung cancers presented in the trachea, in the carina, or in a main stem bronchus (70.7%). This location was observed more often (82.5%) for ACC tumors compared with MEC tumors (44.4%). Involvement of the lymph nodes was observed in 20% of patients and was more common among the patients with ACC (30.8%). Distant metastases were observed in 30.4% of the patients (15 patients in the ACC group [40.5%] compared with only 2 patients in the MEC group [10.5%]; P = .03). For patients who underwent complete surgical resection, the 3-, 5-, and 10-year survival rates were 82%, 70%, and 63%, respectively. The survival rates for surgical MEC patients were 94% at 3 years and 87% at both 5 years and 10 years. For surgical ACC patients, the survival rates were 73%, 57%, and 45% at 3, 5, and 10 years, respectively. The survival rate for patients with ACC who did not undergo surgery was 74% at 3 years, 53% at 5 years, and 31% at 10 years. The difference in survival between surgical and nonsurgical patients was statistically significant (P < .01).

Conclusions: Patients with MEC and ACC frequently have a good long-term prognosis but do not always have indolent diseases. Local recurrence is likely if complete surgical resection is not achieved. ACC has a higher likelihood than MEC to metastasize. Overall, patients with MEC survive better than patients with ACC.