There is a lack of prospective studies evaluating the long-term course and causes of death of MEN1 patients at present. This lack of information is a particular problem at present because there have been numerous widespread treatment changes over the last few years that have altered the late course of MEN1, and have likely altered the causes of death. These changes include the increased ability to control various hormone excess states that were a frequent cause of death in early studies of MEN1 patients,15,43,72,73,83,88,158,180,188,224,225,240,254,279,307,353,366,386,399,438,444,458,461,465,466 accounting for up to 73%–91% of all deaths in some early series.15,195,224,254,444 These include particularly the ability to treat the gastric acid hypersecretion in Zollinger-Ellison syndrome (ZES), earlier diagnosis and better treatment of insulinomas, and the increased use of somatostatin analogues or other treatments for other hypersecretory states (vasoactive intestinal peptide secreting tumors [VIPomas], etc). This also includes an understanding of the diffuse nature of the parathyroid disease in these patients resulting in HPT, which almost all patients develop early in the disease course, and the development of effective treatment with multigland parathyroidectomies, which prevents the development of nephrolithiases, and renal failure,54,57,78,129,149,150 which not infrequently occurred in earlier series.15,32,68,88,129,224,285,438,444,465,466 Similarly, the recognition of the pituitary disease and more aggressive treatments have made this a rare cause of morbidity and death at present compared to in earlier studies.49,129,150,222,378,379,465 Lastly, it is now recognized that MEN1 patients develop neoplasms other than those classically described, such as various carcinoid tumors, CNS tumors, skin tumors, and soft tissue tumors. Of these the carcinoid tumors can be of concern because they can be aggressive and develop later in the disease course.34,40,94,131,150,151,253,326,360,465 The thymic carcinoids, which are rarely reported before 1990, are of particular concern, especially in males, because as a group they are the most aggressive tumors that MEN1 patients develop and are an increasing cause of death, later in the disease course.111,130,131,151,408,413,414,465 With the effective treatment of hormone excess states, they are becoming increasingly important.