In May 2007, William became president of the hospital, a position Diana previously held. Royal Marsden is the first hospital in the world dedicated to cancer treatment and research, and Diana became president in 1989. She regularly visited sick patients and supported its cancer treatment and research work, and William felt proud to carry on his mother's work. "The Royal Marsden does an extraordinary job in treating thousands of cancer patients every year. The standards of care and compassion of its staff are unsurpassed in the world," he said in a statement.
In January 2008, the royal visited the Chelsea hospital just days after a fire swept through the building and damaged several operating rooms. In addition to spending time with the staff and patients, he later returned to open the endoscopy unit and the Oak Centre For Children and Young People with the Duchess of Cambridge. In 2013, William recorded a special video message for Royal Marsden, in which he praised the hospital for all of its hard work. "I am extremely proud to be president of The Royal Marsden, an incredible hospital and a world-class cancer centre carrying out groundbreaking work influencing the treatment of cancer patients all over the UK," he said.