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.