Genomic analysis defines distinct pancreatic and neuronal subtypes of lung carcinoid

Lung carcinoids (L‐CDs) are rare, poorly characterised neuroendocrine tumours (NETs). L‐CDs are more common in women and are not the consequence of cigarette smoking. They are classified histologically as typical carcinoids (TCs) or atypical carcinoids (ACs). ACs confer a worse survival. Histological classification is imperfect, and there is increasing interest in molecular markers. We therefore investigated global transcriptomic and epigenomic profiles of 15 L‐CDs resected with curative intent at Royal Brompton Hospital. We identified underlying mutations and structural abnormalities through whole‐exome sequencing (WES) and single nucleotide polymorphism (SNP) genotyping. Transcriptomic clustering algorithms identified two distinct L‐CD subtypes. These showed similarities either to pancreatic or neuroendocrine tumours at other sites and so were named respectively L‐CD‐PanC and L‐CD‐NeU. L‐CD‐PanC tumours featured upregulation of pancreatic and metabolic pathway genes matched by promoter hypomethylation of genes for beta cells and insulin secretion (p