AB017. Clinicopathologic features, treatment outcomes, and survival in thymic neuroendocrine tumors: a 25-year single-center experience

Background: Thymic neuroendocrine tumors (TNETs) are rare, aggressive neoplasms with limited prospective data guiding optimal management. We aimed to analyze clinicopathologic features, treatment outcomes, and survival of TNET patients treated at a single comprehensive cancer center over 25 years.

Methods: A retrospective review of 19 adult patients with TNETs diagnosed between 2000 and 2024 was conducted. Demographic, clinical, histological, treatment, and survival data were collected from medical records. Survival outcomes, including overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS), were analyzed using the Kaplan-Meier method.

Results: The median age at diagnosis was 52 years (range, 24–73 years), with 12 patients (63.2%) being male. Atypical carcinoid was the most common histological subtype, diagnosed in 10 patients (52.6%), followed by large cell neuroendocrine carcinoma in 6 patients (31.6%). Symptoms were reported in 73.7% of patients at diagnosis, with dyspnea and chest pain being the most common manifestations. Paraneoplastic syndromes were observed in 26.3% of cases, with clinically confirmed Cushing’s syndrome in 15.8%. Treatment modalities and outcomes are summarized in Table 1. Curative intent treatment was performed in 9 patients (47.4%), whereas 10 patients (52.6%) received palliative treatment. Radical surgery was attempted in 8 patients. Complete (R0) resection was achieved in 2 cases (22.2%), while microscopic residual disease (R1) was present in six cases. Postoperative radiotherapy was administered to 7 patients, with doses ranging from 4,600 to 6,000 cGy. Adjuvant chemotherapy, consisting of a cisplatin-etoposide regimen, was used in 3 patients. Among patients treated with palliative intent, 8 received systemic chemotherapy, mainly based on cisplatin-etoposide combinations, and 2 patients received best supportive care. During follow-up, disease recurrence was observed in 4 (44.4%) of the 9 patients initially treated with curative intent. Of these, one patient underwent salvage radical-intent therapy, while three patients received palliative treatment following recurrence. In the group of patients who received palliative treatment, disease progression occurred in 8 patients (80%). After progression, 7 patients received further active palliative therapy, whereas one patient was managed exclusively with best supportive care. Post-progression radiotherapy was administered to 3 patients, and 4 patients received chemotherapy. For the entire cohort, the median OS was 127 months [95% confidence interval (CI): 33–170]. In the curatively treated group, the median PFS was 90 months (95% CI: 42–90), and the median OS was 170 months (95% CI: 127–170). Among patients treated with palliative intent, the median PFS was 11 months (95% CI: 3–105), and the median OS was 33 months (95% CI: 2–65).

Conclusions: TNETs are aggressive tumors associated with high rates of recurrence and progression despite multimodal treatment strategies. Complete surgical resection remains the cornerstone of curative therapy. Palliative treatment yields poor long-term outcomes, highlighting the urgent need for new therapeutic approaches and prospective studies to improve survival in this rare entity.

Keywords: Thymic neuroendocrine tumors (TNETs); thymic carcinoids; surgery; survival outcomes; recurrence