Neuroendocrine tumors of the thymus: a clinicopathological and prognostic study.

BACKGROUND: Neuroendocrine tumors of the thymus are rare, histologically diverse neoplasms with an unpredictable clinical behavior. This study provides a useful clinicopathological classification and determines the relevance of specific prognostic factors. METHODS: Ten neuroendocrine tumors of the thymus were analyzed for specific clinical and pathological features. Prognostic factors of these cases and 71 previously published cases were evaluated by Kaplan-Meier survival curves and Cox multivariate hazard model. RESULTS: There were 7 males and 3 females, with ages ranging from 26 to 77 years. Cases were classified as carcinoid tumor (2), atypical carcinoid tumor (6), and small cell carcinoma (2). An advanced clinical stage was evident in all instances with frequent recurrence (4) and metastases (8), and a short disease-free survival. Overall mortality was 60%. Statistical analysis of current and previously published cases (n = 81 total) revealed that unresectability (p = 0.0001), extent of surgical resection (p = 0.0002), and advanced clinical stage at presentation (p = 0.03) were associated with higher mortality. By multivariate Cox regression analysis, unresectability (p = 0.02) and advanced clinical stage (p = 0.03) were associated with decreased survival. CONCLUSIONS: Neuroendocrine tumors of the thymus can be classified into distinct clinicopathological entities, and specific factors have prognostic relevance.