Filosso PL, Öbergrather K, Malczewska A, et al. - As a biopsy or an operation is required for diagnosing lung neuroendocrine neoplasia (NEN), researchers here appraised a ‘liquid biopsy’ (NETest) as an in vitro diagnostic tool for recognizing NEN and compared it to chromogranin A (CgA). Four study cohorts were assessed: patients with bronchopulmonary carcinoids (n = 99, including 62 typical and 37 atypical carcinoids), lung cancers [n = 101, including 41 adenocarcinomas, 37 squamous carcinomas (SQC), 16 small-cell lung cancers and 7 large-cell neuroendocrine carcinomas]; benign disease (50 idiopathic pulmonary fibrosis) and healthy controls (n = 102). Findings support the efficacy and accuracy of the gene-based liquid biopsy for diagnosing lung tumors with neuroendocrine gene expression. CgA was identified to have no value. They identified a NETest score > 40 as valuable for an accurate (94–97%) rule-in for the diagnosis of NEN and a rule-out for benign and other neoplastic diseases. Given that neuroendocrine gene expression is correlated with a poor prognosis, NETest levels seem to be valuable both in the diagnosis of and the treatment stratification for lung neoplasia.