Outcome of primary neuroendocrine tumors of the thymus: A joint analysis of the International Thymic Malignancy Interest Group and the European Society of Thoracic Surgeons databases

Objective: Primary neuroendocrine tumors of the thymus (TNET) are exceedingly rare. We studied a large series of TNET identified through the International Thymic Malignancy Interest Group and the European Society of Thoracic Surgeons databases. Methods: This was a retrospective multicenter study of patients undergoing operation for TNET between 1984 and 2012. Outcome measures were: overall survival (OS) and cumulative incidence of recurrences (CIR). OS was analyzed using the Kaplan-Meier method and CIR was analyzed using competing risk analysis. Associations with clinical and prognostic factors for OS and CIR were evaluated using the log rank test and Gray test. Results: Two hundred five patients with TNET were treated: 25 patients received induction therapy (19 chemotherapy [CT] and 6 radiotherapy [RT]). Data about resection status were available in 47% of cases: complete resection was performed in 52 patients (54%). Masaoka-Koga stages I, II, III, and IV were observed in 12, 33, 56, and 47 patients, respectively. Atypical carcinoid was the commonest histologic subtype (71 cases; 40%). One hundred one patients with TNET received adjuvant treatment; 52 patients died and 36 experienced a recurrence. The median OS was 7.5 years; 5-year OS was 68%, and 5-year CIR was 39%. OS was significantly influenced by Masaoka-Koga stage (P = .02) and completeness of resection (P = .03). CIR significantly increased in high Masaoka-Koga stages (P = .04). Histologic subtype was not associated with either OS or CIR. Conclusions: Our results confirm the high biologic aggressiveness of these rare neoplasms; pathologic stage and completeness of resection were demonstrated to be strong prognostic factors, whereas histology did not influence patients outcome.