In a space of 12 months, Central Floridians will see leaders who have been at the helm of three top health institutions for more than two decades leave, and make way for a new generation of leaders. Florida Health Care Coalition's new president, Karen van Caulil, assumed her position in October and replaced Becky Cherney, who stepped down after 27 years. Health Central's top executive, Richard Irwin, will leave his post of 25 years at the end of March, and businessman Ken Harker will take on part of those duties. And this summer M.D. Anderson Cancer Center-Orlando President Dr. Clarence Brown will hand the reins to Dr. Mark Roh.