Britain’s King Charles III has been diagnosed with cancer and will step back from public-facing duties while he undergoes treatment, Buckingham Palace announced Monday. The update came after Charles, 75, attended a London hospital for a corrective procedure for an enlarged prostate last month. Tests were carried out and revealed a “form of cancer,” the palace said in a statement on Monday. A royal source told CNN that the form of cancer detected was not prostate cancer, but did not specify further. “His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties,” the palace said. “Throughout this period, His Majesty will continue to undertake State businessand official paperwork as usual,” it added. The King spent three nights at the London Clinic, a private hospital near Regent’s Park, for his recent procedure and was previously said to be “doing well” following the stint. He was seen for the first time since his treatment on Sunday, appearing in good spirits as he waved to the public on his way to a Sunday morning church service in Sandringham, Norfolk. His wife, Queen Camilla, accompanied him. The royal source added that the King returned from Sandringham on Monday morning to begin outpatient treatment in London. “The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure,” Buckingham Palace’s statement said. “He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible.” “His Majesty has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer,” the palace concluded. How the cancer was discovered while the King was being treated for an enlarged prostate is still unknown. CNN medical analyst Dr. Jonathan Reiner said that when patients are admitted to the hospital, they often get tests, like chest x-rays, that could reveal another health issue. “It sounds like in the course of the routine evaluation part for his prostate surgery, they discovered something else was amiss,” Reiner said. Charles became monarch on the death of his mother, Queen Elizabeth II, in September 2022. Prince William, the next in line to the throne, will be returning to public duties later this week, after taking time off to support his wife in her own recovery from abdominal surgery, Kensington Palace announced in a press statement earlier Monday. William is in regular contact with his father, according to a source close to the Prince of Wales. Prince Harry spoke to his father about the diagnosis and will be traveling to the UK to see the King in the coming days, the office of the Duke and Duchess of Sussex said. Harry and Charles have been involved in a long-running, public falling out in the years since the prince and his wife Meghan, Duchess of Sussex, stepped back from royal duties, though the duke did make a brief visit to the UK for Charles’ coronation last year. Britain’s political leaders quickly reacted to the news. Rishi Sunak, the prime minister, wrote on social media that he was “wishing His Majesty a full and speedy recovery.” “I have no doubt he’ll be back to full strength in no time and I know the whole country will be wishing him well,” Sunak said. US President Joe Biden meanwhile said he is “concerned” about King Charles. “I’m concerned about him. Just heard about his diagnosis,” Biden said in Las Vegas when asked about the development. Biden said he expected to speak soon with the King, “God willing.” The leaders of Commonwealth nations, like Canada and Australia, as well as French President Emmanuel Macron, also offered their support to the King. “Wishing His Majesty King Charles III a speedy recovery. Our thoughts are with the British people,” Macron wrote in a post on X. Health drama worsens for royals Monday’s announcement from Buckingham Palace – made in the early evening in London – marked a major and unwelcome milestone in Charles’ reign as Britain’s monarch. It exacerbated an already challenging period for the royal family, whose new year has been marked by health-related issues that had left three of their most senior members sidelined. Charles’ prostate operation required a three-day hospital visit, during which the tests that revealed cancer were conducted. Queen Camilla, who had visited her husband daily, was by his side as he left last Monday. Camilla previously said her husband was “fine” and “looking forward to getting back to work” while on recent engagements. Catherine, Princess of Wales, had simultaneously been dealing with abdominal issues and left the same hospital hours earlier after her operation. She had been admitted to hospital on January 16 for a planned abdominal surgery. A day later, Kensington Palace announced the operation was a success and would remain in hospital for 10 to 14 days. It is unclear what the surgery was for, but a royal source told CNN that the 42-year-old’s condition was non-cancerous. Since then, Kate and her husband, Prince William, have been removed from public view while they focused on her recovery. William and Kate both cleared their diaries of public duties until at least Easter, but on Monday afternoon – hours before Charles’ diagnosis was made public – Kensington Palace announced that William would resume engagements later this week. Sarah Ferguson, Duchess of York, was also diagnosed with malignant melanoma, an aggressive form of skin cancer, last month. Charles had generally enjoyed good health and is known for enjoying long walks in the countryside; he contracted Covid-19 twice, in 2020 and 2022, but recovered in good time on each occasion. If the King were to become so ill that he is unable to carry out his full duties on a temporary basis, he would be able to delegate some of them to two or more Counsellors of State. The current Counsellors of State are Camilla, William, Harry, Princess Anne, Prince Edward, Prince Andrew, and Princess Beatrice. If the King became completely unable to carry out his constitutional duties, to the point where the state could no longer function properly, his powers can be withdrawn and assumed by a regent. Under a 1937 law, that would be the next in line to the throne, which is Prince William.