For comparison of pulmonary versus extra-pulmonary NEC, Bergsland et al. [33] conducted genomic analysis of ~600 SCLC cases and 270 poorly differentiated GEP-NEC cases, and showed that TP53 and RB1 mutations were prominent in SCLC (90% and 67%, respectively), MEN1 and DAXX mutations were frequent in pancreatic NEC (33% and 20%, respectively), and APC and KRAS mutations were often noted in colon NEC (47% and 37%, respectively. This evidence concerns the gene RB1 and small cell lung carcinoma.