Clinical Features and Prognosis of Thymic Neuroendocrine Tumors Associated with Multiple Endocrine Neoplasia Type 1: A Single Center Study, Systematic Review, and Meta-analysis.

ObjectiveThymic neuroendocrine tumour (TH-NET) accounts for almost 20% of multiple endocrine neoplasia type 1 (MEN1)-associated mortality. Identifying risk factors for the development of these rare tumours and prognostic factors for clinical outcomes will be helpful in clinical practice. Design and PatientsWe performed a retrospective analysis of patients treated for TH-NET associated with MEN1 in a single institution and meta-analysis of literature reports. We used a fixed effect model to pool results across studies to evaluate the prevalence, clinical features and prognosis. ResultsTH-NET was detected in 9 (7.4%) of 121 patients with MEN1 seen in our institution, and 5 (55.6%) were women. Seven additional studies were identified through a systematic review of the literature. The pool estimate of TH-NET prevalence was 3.7% (n=99) in MEN1 (n=2710), sex ratio was 79:20 (male vs female), and the median age at diagnosis was 43.0years (range, 16.0-72.0years). Forty-three patients died with a median survival time of 8.4years. Older age at diagnosis (HR=1.4, 95% CI=1.0-1.8, P=.03), maximum tumour diameter (HR=1.5, 95% CI=1.0-2.3, P=.04) and presence of metastasis (HR=1.6, 95% CI=1.0-2.5, P=.04) were associated with worse outcome. A male predominance (91.9% vs 59.5%, P<.001) and history of smoking (59.0% vs 23.5%, P=.015) were more common in American/European series compared to Asian reports. ConclusionTH-NET is a rare but fatal component of MEN1. Earlier detection of TH-NET in patients with MEN1 may be recommended which should theoretically result in better outcomes. Different genetic backgrounds (race) appear to result in clinical difference.