LONDON, FEBRUARY 6

British Prime Minister Rishi Sunak said Tuesday that he was "shocked and sad" to learn that King Charles III has cancer, but is relieved that the illness was caught early.

Buckingham Palace announced Monday evening that the king has begun outpatient treatment for an undisclosed form of cancer. It was found during his recent treatment for an enlarged prostate but is not connected to that condition, the palace said.

"Thankfully, this has been caught early," Sunak told BBC radio, adding that as prime minister he would "continue to communicate with him as normal."

"He'll just be in our thoughts and our prayers. Many families around the country listening to this will have been touched by the same thing and they know what it means to everyone," Sunak said. "So we'll just be willing him on and hopefully we get through this as quickly as possible."

Less than 18 months into his reign, the 75-year-old monarch has suspended public engagements but will continue with state business - including weekly meetings with the prime minister - and won't be handing over his constitutional roles as head of state.

The palace said Charles, who has generally enjoyed good health, "remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible."

Charles became king in September 2022 when his mother, Queen Elizabeth II, died at the age of 96 after 70 years on the throne.

News of the king's diagnosis comes as his daughter-in-law Kate, Princess of Wales, recovers from abdominal surgery that saw her hospitalized for about two weeks.

Kate is still taking a break from royal duties as she recovers. Her husband, Prince William, who is heir to the throne, also took time off to help look after her and the couple's three children, but is due to preside over an investiture ceremony at Windsor Castle and a charity dinner on Wednesday.

The king's younger son, Prince Harry, who quit royal duties in 2020 and moved to California, has spoken to his father about the diagnosis and "will be traveling to the U.K. to see His Majesty in the coming days," said the office of Harry and his wife, Meghan.

World leaders sent the monarch good wishes, including U.S. President Joe Biden, who tweeted: "Jill and I join the people of the United Kingdom in praying that His Majesty experiences a swift and full recovery."

Charles departed from royal tradition with his openness about his prostate condition. For centuries Britain's royal family remained tight-lipped about health matters.

Disclosing information about his cancer diagnosis - albeit in a limited way - is another break with tradition.

Buckingham palace said that the king "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."