The poorly differentiated NET or NECs are characterized by a dismal prognosis due to mutation and inactivation of tumor suppressor genes, TP53, RB1, CDKN1 and APC in NEC of GIT origin and inactivation of MEN1, VHL, TSC1/2, and the hyperactivation of the PI3K/mTOR pathway as distinctive biological features of these neoplasms of NEC arising from Pancreas.18,19. Here, RB1 is linked to neuroendocrine carcinoma.