MEN1 and Zollinger-Ellison syndrome: Second, the lifelong period of maintenance acid treatment eventually needed by most ZES patients is long because the average age of ZES onset is between 27–44 years [43,86,125,210] and the mean survival rate is 90% at 25 years after onset in MEN1/ZES patients and >60% in sporadic ZES patients, thus most patients require acid secretory control for >25 years [19,187,211].