Similarly to patients with sporadic NETs/ZES/pNETs, patients with MEN1-ZES/MEN1 require tumor localization studies in all phases of their management, including in some cases for diagnosis; to assess the role of surgery whether for possible cure or cytoreduction; to assess the need for anti-tumor therapy or the response to anti-tumor therapy; and to assess tumor recurrence [8,16,58,118,201,326,462,463,464,465,466,467,468,469]. Here, MEN1 is linked to Zollinger-Ellison syndrome.