Survival comparison of pulmonary neuroendocrine carcinoma, adenocarcinoma with neuroendocrine differentiation, and adenocarcinoma

Background: Pulmonary adenocarcinoma with neuroendocrine differentiation (ADE_ned) is a relatively uncommon pathological classification, and there exists considerable debate regarding its prognosis and treatment. The purpose of this study was to analyze the survival difference between patients with neuroendocrine carcinoma (NEC), adenocarcinoma (ADE), or ADE_ned and to investigate the prognostic factors influencing the outcomes of individuals diagnosed with pulmonary ADE_ned. Methods: We retrieved information on 316 cases of ADE_ned, 188,823 cases of ADE, and 71,154 cases of NEC diagnosed between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. To account for potential confounding variables, propensity score matching (PSM) was employed. Comparative analyses were conducted to estimate the overall survival (OS) and cancer-specific survival (CSS). Finally, the Cox regression models were used to identify prognostic factors associated with pulmonary ADE_ned. Results: Prior to PSM, patients with lung ADE_ned had a worse OS rate than did those with lung ADE or NEC (5-year OS rate: 13.3% vs. 26.6% vs. 15.6%; P<0.001 and P=0.009, respectively). In terms of CSS, the 5-year CSS rate of patients with ADE_ned was superior to that of NEC but inferior to that of ADE (28.7% vs. 26.8% vs. 43.8%; P=0.006 and P<0.001, respectively). Following PSM, the 5-year survival rate of patients with ADE_ned remained lower than that of individuals with ADE or NEC in terms of OS (13.3% vs. 24.4% vs. 23.0%; P<0.001 and P<0001, respectively) and CSS (28.8% vs. 58.6% vs. 43.1%; P<0.001 and P=0.006, respectively). Finally, the results of the competitive risk regression analysis demonstrated that several variables, including sex, T stage, N stage, M stage, and surgery, were found to be independent prognostic factors for patients diagnosed with pulmonary ADE_ned (all P values <0.05). Conclusions: Patients with lung ADE_ned had a significantly poorer survival outcome compared to those with lung ADE or NEC. Furthermore, sex, tumor-node-metastasis (TNM) stage, and surgery were found to be independent prognostic indicators for cases with lung ADE_ned.