Treatment and Prognosis of Thymic Neuroendocrine Neoplasms in the United States

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BACKGROUND Primary thymic neuroendocrine neoplasms (TNEN) are rare and understudied. Here we assess TNEN treatment and prognosis in the United States. METHODS TNEN diagnosed between 2004 and 2023 in the National Cancer Database was compared to thymic carcinoma and thymoma. Stage was abstracted into TNM AJCC 8 th Edition. Survival was modeled by Kaplan-Meier analysis and Cox proportional hazards. RESULTS 1,029 TNEN cases were compared to 14,641 thymoma and 5,100 thymic carcinoma. 579 (56.3%) TNEN patients had surgery, 398 (38.7%) received chemotherapy, and 57 (5.5%) underwent radiation. TNEN presented as localized stage [379 (36.8%)] more often than thymic carcinoma [1386 (27.2%), p<0.001], but less than thymoma [7798 (53.3%), p<0.001]. Five-year survival of surgically resected TNEN was 77.1% (86.1% for thymoma and 65.9% for thymic carcinoma, p<0.001). Resected typical and atypical carcinoids exhibited similar 5-year survival (90.5% vs 85.6%), which was higher than neuroendocrine carcinoma (76.7%, p=0.01). Survival was higher with definitive surgical management for both localized (HR 4.76, 95% CI 2.89-7.81, p<0.001) and advanced tumors (HR 2.26, 95% CI 1.56-3.27, p<0.001). CONCLUSIONS Compared to thymoma and thymic carcinoma, TNEN has an intermediate prognosis, varying based on histology and resectability. Definitive surgical resection is associated with more favorable prognosis in all stages.