NT-proBNP as a neuroendocrine tumor biomarker: beyond heart failure

Introduction: Neuroendocrine tumors (NETs) are rare neoplasms that occur in various locations throughout the body. Despite their usually benign character, they might manifest with distant metastases. N-terminal prohormone of brain natriuretic peptide (NT-proBNP) has previously been described as a useful biomarker in diagnosing carcinoid heart disease (CHD), a common advanced NETs manifestation. We observed plasma concentrations of NT-proBNP in metastatic midgut NETs over a 4-year period. Objectives: We aimed to explore NT-proBNP concentrations in states of varying levels of cell proliferation and disease status. Our goal was to investigate NT-proBNP's role in predicting disease progression in relation to previous research and up-to-date scientific guidelines. Patients and methods: We performed a retrospective multivariate analysis of NT-proBNP concentrations in 41 midgut NETs patients treated with somatostatin analogs, all with liver metastases. NT-proBNP concentrations were measured in every patient across 16 evenly distanced time points over a 48-month period and were compared to variables such as sex, age, grading, Ki-67, primary tumor location, and CT findings. Results: NT-proBNP concentrations correlated positively with higher liver tumor burden, higher grading, high Ki-67 levels, and with progressive disease in CT. There were no differences in NT-proBNP levels with regard to primary location (ileum vs jejunum), sex, and age. Conclusion: We conclude that NT-proBNP is a useful analyte for monitoring NETs progression, due to its increased concentration in scenarios implying increased cellular proliferation. These long-term follow-up results align with previous findings and suggest an additional role for NT-proBNP in diagnostic algorithms, beyond a CHD biomarker.