King Charles III’s brief hospital stay reminds UK that monarch is still a cancer patient

King Charles III is driven by car from Clarence House, his London home, along The Mall towards Buckingham Palace in London, Friday, March 28, 2025. (Ben Whitley/PA via AP)

King Charles III waved to well-wishers in central London on Friday as he headed for his country estate in western England a day after he was briefly hospitalized because of side effects from a scheduled cancer treatment.

Charles canceled planned engagements on Thursday afternoon and Friday on the advice of his doctors, Buckingham Palace said, without providing details about the “temporary side effects” that he experienced.

But the episode was a reminder that the king is 76 and continues to undergo treatment for an undisclosed form of cancer diagnosed more than a year ago.

That reality has slipped away from the collective consciousness since last spring, when Charles returned to public duties after stepping away for almost three months to focus on his initial treatment and recovery. In the intervening months, he has attended D-Day commemoration events in France, presided over the State Opening of Parliament and even embarked on a nine-day visit to Australia and Samoa.

But during the early stages of his treatment, Charles continued fulfilling his constitutional duties as head of state, including reviewing government papers and meeting with the prime minister.

Here’s a brief rundown of what we know about the king’s health.

What happened?

The king went to the London Clinic on Thursday morning for a scheduled cancer treatment. The clinic is a private hospital in central London, where Charles has been receiving treatment since his diagnosis in February 2024.

“Following scheduled and ongoing medical treatment for cancer this morning, the king experienced temporary side effects that required a short period of observation in hospital,” Buckingham Palace said in a statement. “His majesty’s afternoon engagements were therefore postponed.”

The king then returned to his home at Clarence House, where he reviewed papers and made calls, the palace said. Queen Camilla didn’t join him at the hospital.

“His majesty would like to send his apologies to all those who may be inconvenienced or disappointed as a result,” the palace said in a statement.

Will this affect future events?

The king is expected to press ahead with his work in the coming days, including a state visit to Italy scheduled for early April.

Why did the palace decide to reveal this information?

Palace officials have recognized that it’s better to release some information about the king’s health, rather than allow media speculation to fill the void when he’s forced to cancel scheduled events.

But they have tried to walk a fine line, seeking to balance the public’s legitimate interest in the health of the head of state with Charles’ right to privacy.

This was seen first in January 2024, when the palace announced Charles was being treated for an enlarged prostate, followed by the cancer diagnosis a few weeks later.

The decision to talk about the king’s health issues marked a departure from past palace protocols. For example, when Queen Elizabeth II began missing events toward the end of her life, royal officials repeatedly said that she was suffering from “mobility issues,” without providing further details. Her death certificate listed the cause as “old age.”

The public was unaware that Charles’ grandfather, King George VI, had lung cancer before his death in February 1952 at the age of 56. Some historians suggest that even the king wasn’t told about the gravity of his condition.

Charles’ decision to break with the past has paid dividends

Health authorities have applauded the king’s openness, saying his disclosures saved lives by encouraging thousands of men to have prostate exams.

Royal experts say Charles’ candor has also brought him closer to the public by demonstrating that he faces the same kinds of challenges that they do. Health is, after all, the great leveler.

Why is Charles doing so much?

Charles’ busy schedule is a reminder that this is a man who waited around seven decades to become monarch and he wants to make the most of it.

The king has been open about his desire to demonstrate that the monarchy still has a role to play as a symbol of unity and tradition in the sometimes fractious, multicultural nation that is 21st-century Britain.

And the job of a modern king is to take part in a whirl of public events, from the pageantry of state occasions when he wears the crown and rides through the streets of London in a horse-drawn carriage to more mundane appearances such as opening public buildings or handing out awards for public service.

Charles took part in 372 public engagements last year, even after stepping aside for almost three months because of cancer treatment, according to data compiled by The Times of London newspaper. That made him the second-busiest royal behind his sister, Princes Anne, who had 474 engagements.

Charles has long been known as a workaholic, and Queen Camilla said last year that he “won’t slow down and won’t do what he’s told.” During her Reading Room literary festival in July, the queen told author Lee Child that her husband was “doing fine,” but hadn’t heeded her advice to curtail his schedule.

Prince Harry once said that his father worked so hard that he would fall asleep at his desk and wake up with bits of paper stuck to his face.

What are royal experts saying?

The king’s busy schedule has obscured the fact that he is an older man with cancer, said Robert Hardman, author of “Charles III: New King, New Court, the Inside Story.”

“We’ve seen him go back to normal,” Hardman told the BBC on Friday.

“I think this is sort of a reminder that this is a head of state undergoing treatment for cancer, because I think a lot of us tended to forget it.”