Progastrin-Releasing Peptide As a Diagnostic Biomarker of Pulmonary and Non-Pulmonary Neuroendocrine Neoplasms

BackgroundProgastrin-releasing peptide (ProGRP) is the precursor of the gastrin-releasing peptide, a neuropeptide secreted by cells of neural and endocrine origin. Recently, ProGRP has emerged as a circulating biomarker for small cell lung cancer (SCLC), a subtype of aggressive and poorly differentiated neuroendocrine neoplasm (NEN). Given the ability of the neuroendocrine SCLC cells to secrete this peptide, we performed an in-depth narrative review aimed at collecting, summarizing, and critically analyzing the available literature about the possible value of ProGRP as a biomarker for pulmonary NENs other than SCLC, and for NENs of non-pulmonary origin.MethodsWe conducted an extensive search on international databases (PubMed, Web of Science, and Scopus).ResultsWe selected 21 pertinent published articles (12 original studies and 9 case reports). Overall, the original studies included 1,711 patients, and the case reports described the clinical course of 10 patients.ConclusionThe data analyzed suggest a potential role for ProGRP as a diagnostic biomarker for typical and atypical lung carcinoids, pulmonary large cell neuroendocrine carcinoma, medullary thyroid carcinoma, non-pulmonary neuroendocrine carcinomas, prostate cancer with neuroendocrine differentiation, and the pancreatobiliary neuroendocrine carcinoma. Despite these promising results, additional studies are needed, to clarify the role of ProGRP as the diagnostic biomarker for specific NENs.