Objective: Although rare, thymic neuroendocrine tumors (TNET) and thymic carcinoma (TC) are the most common thymic nonthymomatous malignancies; their survival outcomes have not been thoroughly compared. We analyzed the clinical, treatment, and survival characteristics of TNET and TC.
Methods: We retrospectively identified patients with a histologic diagnosis of TNET or TC in the National Cancer Database (2004 to 2015). Exclusion criteria were age <18 years and unstaged tumors. Descriptive statistics, survival analysis, and multivariable Cox regression analyses were used in elucidating associations.
Results: One thousand four hundred eighty-nine patients were included (TNET: 19.8%). Patients with TNET were significantly younger (57 vs 62.5 years), more likely to be male (70.5% vs 60.0%), and have localized tumors (45.4% vs 32.3%). Patients with TC more frequently underwent chemotherapy (56.1% vs 34.9%), radiation (56.9% vs 39.3%), and trimodality therapy (21.3% vs 11.5%), while resection rates were similar (55.3% vs 58.3%). The 5-year survival was 62% for TNET and 52% for TC, but comparable following multivariable adjustment. Age, stage, and Charlson-Deyo score were negative predictors of survival, while surgery and trimodality therapy were positive predictors. On subanalysis, adjuvant radiation therapy (ART) improved the survival of margin-positive tumors and was an independent predictor of survival for both tumor types (hazard ratio = 0.5).
Conclusions: Our analysis of the largest series of TNET and TC showed a survival rate surpassing 50% at 5 years. These outcomes seem to be influenced by surgical resection and ART. Standardized staging and surgical protocols including lymph node sampling are still warranted to better elucidate the treatment algorithm of these tumors.
Keywords: chemotherapy; radiation; surgery; survival; thymus.