Clinical features and prognosis of thymic neuroendocrine tumours associated with multiple endocrine neoplasia type 1: A single-centre study, systematic review and meta-analysis

Objective: Thymic 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 Patients: We 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. Results: TH-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 43.0 years (range, 16.0-72.0 years). Forty-three patients died with a median survival time of 8.4 years. 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. Conclusion: TH-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.