Primary lung mucoepidermoid carcinoma: analysis of prognostic factors using surveillance, epidemiology and end results program

Mucoepidermoid carcinoma (MEC) primarily occurs in salivary glands, but can also arise in other organs; however, the impact of primary location on patient prognosis is largely unknown.Using Surveillance, Epidemiology and End Results Program (SEER) data we investigated whether the clinical and prognostic features of MEC differed among multiple organ sites. The SEER-18 dataset from 18 cancer registries in the US between 1972 and 2012 was chosen. The common organ sites with 100 or more cases were further analyzed. Survival analysis included Log-rank tests of Kaplan-Meier curves and univariate/multivariate proportional hazard analysis.A total of 7,191 MEC cases with survival data were identified in the SEER data. Major salivary gland (MSG) was the primary site in 52.9% of cases, followed by gum and other mouth (23.6%), lung (5.9%), tongue (3.4%) and others. Compared to MSG-MEC, primary lung MEC had significantly more patients with age <=70, diagnosis in 2002 and earlier, distant stage, undetermined grade and nonsurgical treatment. Primary lung MEC, older age, male gender, early year of diagnosis, distant stage, high histologic grade and radiation alone were significantly associated with poor 5-year disease-specific survival rate. Among patients with primary lung MEC, univariate analysis demonstrated that those with main bronchus or upper lobe primary sites had significantly decreased 5-year disease-specific survival rate.This study suggests that there is a major difference in prognosis of MEC among primary sites. Primary lung MEC might have poor prognosis over MSG-MEC.