Prince William is expected to cover some engagements on his father’s behalf while the King receives medical care.
Few details about the King’s prognosis have been disclosed but the Palace has confirmed that while the illness was identified during enlarged prostate treatment, it is not prostate cancer.
He began “regular treatments” for his condition on Monday, the Palace said.
Although he will pause his public appearances, the King will continue with his constitutional role as head of state, including paperwork and private meetings.
It is understood the King’s weekly audiences with prime minister Rishi Sunak will continue and will be in person, unless doctors advise that he limits such contact.
The Palace added that Charles “remains wholly positive” about his treatment and “looks forward” to returning to public duty.
The King informed both his sons personally about his diagnosis and the Prince of Wales is said to be in regular contact with his father.
The Duke of Sussex, Prince Harry, who lives in the United States, spoke to his father and will be travelling to the UK to see him in the coming days.
The King returned to London from Sandringham in Norfolk on Monday morning and the palace says he has started treatment as an outpatient.
