To investigate further prognostic factors that might be associated with an MEN1-related death, we compared various clinical, laboratory, and tumoral features of MEN1 and ZES for the NIH MEN1/ZES patients classified as having either an MEN1-related death or a non-MEN1-related death. We compared the clinical and laboratory features of MEN1 or ZES and tumoral features that were compared in the NIH patients by survival status in Tables 5 and 6 in patients who had either an MEN1-related death or a non-MEN1-related death (Tables 7 and 8). We found no significant differences for any of the 34 clinical or laboratory characteristics compared. In particular, there was no significant difference in fasting gastrin level, duration, or other features of various MEN1-related manifestations, many of which have been reported to have prognostic significance in some studies.46,54,71,141,151,152,414,465 In contrast, for a number of the tumoral features in the NIH patients, there was a significant difference between patients who did or did not have an MEN1-related death. Specifically, of the 42 tumor features compared, those significantly associated with an MEN1 disease-related death included an increased primary tumor size (p = 0.0203), particularly >3 cm (p = 0.0042); the presence of liver metastases (p = 0.0180), bone metastases (p = 0.0180), or any distant metastases (p = 0.0180); the number of PET lesions initially imaged, particularly if ≥2 were seen (p = 0.0180); a younger age of developing liver metastases (p = 0.028); the development of any new lesions during follow-up (p = 0.0180); the development of liver metastases during follow-up (p = 0.0180); or the presence of tumors demonstrating aggressive growth (p = 0.0001). Whether a previous PET resection occurred has been reported to be an important tumor feature in some studies of NIH MEN1/ZES patients22,150,195,217,217,234 and to have prognostic significance; however, we did not find it to be important in the current study as a prognostic factor for an MEN1-related death (p = 0.30). Similarly, in contrast to sporadic ZES, a number of tumoral features reported to have prognostic value for disease-related death118,191,201,279,287,320,459,476 were not found to be associated with an MEN1/ZES-related death in the current study, including the presence of a pancreatic PET rather than a duodenal PET (p = 0.47); the presence of any pancreatic PET (p = 0.44); the failure to undergo a PET resection (p = 0.30); or the presence of lymph node metastases (p = 0.56).