Histologic and molecular features of small well-differentiated pancreatic neuroendocrine tumors associated with the development of liver metastases

The incidence of neuroendocrine neoplasms (NEN) has grown by a factor of 6.4 between 1973 and 2012 (1). According to the United States Surveillance, Epidemiology, and End Results (SEER), some 50% of all NEN, 3.56×10⁵, are gastroenteropancreatic (GEP) in origin, including 1.05, 10.4, 0.48×10⁵ of the small intestine, rectum, and pancreas, respectively. Like the Spanish group, others have reported a higher incidence of pancreatic NEN (P-NEN) (2). Given its typically indolent course, GEP-NENs are the second most prevalent tumors of the digestive system, surpassed only by colorectal cancer, underscoring the importance of understanding them, their diagnosis, and efficient treatment strategies.