Genomic aberrations in TP53 and RB1 have also been observed in GEP-NEC at frequencies ranging from 57 to 89% and 9 to 46%, respectively [10–12, 29, 52–57], thus supporting the idea that the NEC phenotype shares part of the genetic processes of tumor evolution, regardless of the anatomic site of tumor origin [5, 30]. This evidence concerns the gene RB1 and neoplasm.