Molecular identification of bronchopulmonary neuroendocrine tumours and neuroendocrine genotype in lung neoplasia using the NETest liquid biopsy
Pier Luigi Filosso, Kjell Öberg, Anna Malczewska, Anna Lewczuk, Matteo Roffinella, Harry R. Aslanian, Lisa Bodei
Abstract
OBJECTIVES: Diagnosing lung neuroendocrine neoplasia (NEN) requires a biopsy or an operation. We evaluated a 'liquid biopsy' (NETest) as an in vitro diagnostic tool for identifying NEN and compared it to chromogranin A (CgA). METHODS: We identified 4 study cohorts: 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). Transcript levels measured quantitatively (activity scores: 0-100) were compared to CgA (enzyme-linked immunosorbent assay; normal < 109 ng/ml) levels. RESULTS: The results of the NETest were positive (>20) in 94% of patients with bronchopulmonary carcinoid compared to 8% of the controls (Fisher's exact test; P < 0.001) and were significantly more accurate as a diagnostic test (McNemar's test; P < 0.001, χ2 = 72) than was CgA (positive: 19% bronchopulmonary carcinoid, 15% controls). Small-cell lung cancers (87%), large-cell neuroendocrine carcinomas (86%), adenocarcinoma (42%) and SQC (35%) were also NETest-positive. Increasing the NETest cut-off score to >40 was useful for detecting all NENs and differentiating these tumours from either controls/benign lung diseases (specificity 97%) or adenocarcinoma/SQC (specificity 94%). CgA was positive in 15-44% irrespective of pathology and had no diagnostic value. CONCLUSIONS: A gene-based liquid biopsy is an effective and accurate method for diagnosing lung tumours with neuroendocrine gene expression. CgA has no value. An NETest score >40 provides an accurate (94-97%) rule-in for the diagnosis of NEN and a rule-out for benign and other neoplastic diseases. Because neuroendocrine gene expression is associated with a poor prognosis, NETest levels may have utility both in the diagnosis of and the treatment stratification for lung neoplasia.