The Management and Outcomes of Patients with Extra-Pulmonary Neuroendocrine Neoplasms and Brain Metastases

Background: Brain metastases (BMs) in patients with extra-pulmonary neuroendocrine neoplasms (EP-NENs) are rare, and limited clinical information is available. The aim of this study was to detail the clinicopathological features, management and outcomes in patients with EP-NENs who developed BMs. Methods: A retrospective single-centre analysis of consecutive patients with EP-NENs (August 2004-February 2020) was conducted. Median overall survival (OS)/survival from BMs diagnosis was estimated (Kaplan-Meier). Results: Of 730 patients, 17 (1.9%) had BMs, median age 61 years (range 15-77); 8 (53%) male, unknown primary NEN site: 40%. Patients with BMs had grade 3 (G3) EP-NENs 11 (73%), G2: 3 (20%), G1: 1 (7%). Eight (53%) had poorly differentiated NENs, 6 were well-differentiated and 1 was not recorded. Additionally, 2 (13%) patients had synchronous BMs at diagnosis, whilst 13 (87%) developed BMs metachronously. The relative risk of developing BMs was 7.48 in patients with G3 disease vs. G1 + G2 disease (p = 0.0001). Median time to the development of BMs after NEN diagnosis: 15.9 months (range 2.5-139.5). Five patients had a solitary BM, 12 had multiple BMs. Treatment of BMs were surgery (n = 3); radiotherapy (n = 5); 4: whole brain radiotherapy, 1: conformal radiotherapy (orbit). Nine (53%) had best supportive care. Median OS from NEN diagnosis was 23.6 months [95% CI 15.2-31.3]; median time to death from BMs diagnosis was 3.0 months [95% CI 0.0-8.3]. Conclusion: BMs in patients with EP-NENs are rare and of increased risk in G3 vs. G1 + G2 EP-NENs. Survival outcomes are poor, and a greater understanding is needed to improve therapeutic outcomes.