Thymic neuroendocrine tumors in multiple endocrine neoplasia type 1: A comparative study on 21 cases among a series of 761 MEN1 from the GTE (Groupe des Tumeurs Endocrines)

Background: Thymic neuroendocrine tumors (Th-NET) present a poor prognosis for patients with multiple endocrine neoplasia type 1 (MEN1). The purpose of this article was to study the clinical, biological, and pathological features of Th-NET in a large cohort of patients with MEN1. Methods: The 761-patient MEN1 cohort from the GTE registry was used (Groupe des Tumeurs Endocrines). Results: The actuarial probability of occurrence was 2.6% (range, 1.3-5.5%) at aged 40 years. All, except one, Th-NET patients were men. Four patients had no other associated lesions. The youngest patient was aged 16 years. Mean age at the time of diagnosis was 42.7 (range, 16.1-67.5) years. The 10-year probability of survival was 36.1% (range, 11.5-62%). Seven patients (33%) belonged to clustered MEN1 families. The spectrum of associated lesions in patients with Th-NET was not statistically different from the spectrum of the remainder of the cohort. Various endocrine markers were high, but none were sensitive or specific enough to be useful for Th-NET detection. CT-scan and MRI were always positive at the time of diagnosis. No particular mutation was found to be associated with Th-NET. Five cases underwent prophylactic thymectomy without success. Conclusions: Several end points may be helpful for future guidelines: (1) earlier detection of Th-NET in MEN1 patients is required; (2) screening of both sexes is necessary; (3) a prospective study comparing MRI vs. CT scan in yearly screening for Th-NET is needed; (4) a reinforced screening program must be established for patients who belong to clustered families; and (5) thymectomies must be performed in specialized centers.