Outcome of primary pulmonary salivary gland-type carcinoma

Abstract

Abstract Introduction/Objective Primary pulmonary salivary gland-type carcinomas are rare malignancies that arise from minor salivary gland tissue present within seromucinous submucosal glands within the lower respiratory tract. Due to their rarity (~ <1% of all primary lung malignancies), the epidemiological features and outcome of these malignancies are not well documented. Data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database was analyzed to identify cases of primary pulmonary salivary gland carcinoma. The most common tumor types included mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ADCC), and epithelial-myoepithelial carcinoma (EMEC). The tumors were analyzed for overall survival across various epidemiological factors. Methods/Case Report All patients diagnosed with MEC, ADCC, and EMEC with the lung designated as the primary site between the period of 1975 to 2017 were analyzed. We calculated overall survival and disease-specific survival with Kaplan-Meier curves and Cox proportional hazards models using SPSS v25. Results (if a Case Study enter NA) 323 cases of MEC, 284 cases of ADCC, and 6 cases of EMEC diagnosed as primary lung carcinoma were identified. Age distribution analysis of the patients showed a unimodal distribution for both MEC and ADCC with most patients being diagnosed after the age of 40. 54% of MEC patients were male, while 48% of ADCC patients were male. The majority of patients were Caucasians (77% for MEC and 83% for ADCC patients). Both disease-specific and overall survival were worse for patients diagnosed at the age of 60 years or above. Race or sex did not significantly affect patients’ survival. High-grade MEC showed significantly worse prognosis than low or intermediate grade MEC. EMEC cases were too few (n=6) to perform reliable survival analysis, however, the age of diagnosis was higher (45 and above) with a higher incidence among black population (50%). Conclusion Comprehensive review of clinical and epidemiological features of primary salivary gland-type lung carcinoma show that the age of diagnosis and tumor grade are the most significant factor in determining the survival of these patients.