Clinical, pathological and treatment factors associated with the survival of patients with primary pulmonary salivary gland-type tumors

Abstract

IntroductionPrimary pulmonary salivary gland-type tumors (p-SGTs) are rare, with poorly understood clinicopathological characteristics and survival. There are only few case reports or small case series, and factors associated with survival need to be identified. MethodsA population cohort study was conducted using data from patients with histologically diagnosed primary p-SGTs in the Surveillance, Epidemiology and End Results (SEER) database between 1988 and 2013. Propensity-matching (PSM) analysis was performed to determine overall survival (OS) among patients with different pathological type. A prognostic nomogram was established, and its predictive accuracy and discriminative ability were determined by the concordance index (C-index). ResultsIn total, 462 patients with p-SGT were identified including 315 patients with mucoepidermoid carcinoma (MEC), 139 patients with adenoid cystic carcinoma (ACC) and 8 patients with epithelial-myoepithelial carcinoma (EMC). The 1-, 5-, 10-, and 20-year OS rates of p-SGT patients were 79.6%, 68.5%, 62.7%, and 56.3%, respectively. Log-rank analysis in the matched cohort showed a significantly better prognosis for patients with p-SGT than those with non-SGT lung adenocarcinoma (P < 0.001). Cancer-directed surgery significantly improved median OS (P < 0.01). Radiotherapy did not prolong OS (P = 0.28, P = 0.70). Multivariate Cox analysis showed that older age (>58 years), larger lesions, metastases and poor differentiation were independent prognostic factors for worse survival, while cancer-directed surgery was an independent protective factor (HR = 0.18, 95% CI 0.11–0.29). Patients with MEC were younger with smaller tumors, lower ratio of lymph node or distant metastases as well as earlier stage than those with ACC, and there was no significant difference in survival between MEC and ACC patients. Six independent prognostic factors were identified and incorporated into the nomogram (C-index for survival = 0.88; 95% CI 0.84-0.92). ConclusionPulmonary SGTs are uncommon, and older age, larger lesions, metastases, poor differentiation and cancer-directed surgery are independently associated with prognosis. Early detection and diagnosis increase OS for these patients.