By disclosing his cancer, Charles breaks centuries of royal tradition. But he shares only so much

WATCH: King Charles meets with Rishi Sunak Wearing a navy blue suit and tie, King Charles met with Prime Minister Rishi Sunak for the first time since his cancer diagnosis.

LONDON — In British history, the secrecy of the monarch's health has always reigned supreme. Buckingham Palace's disclosure that King Charles III has been diagnosed with cancer shattered that longstanding tradition.

On the heels of the shock and well-wishing that followed the official statement Monday came the surprise that the palace had announced anything at all. Indeed, the unprecedented missive was sparse on details: Charles, 75, had begun treatment for a cancer it did not name after being diagnosed during a recent corrective procedure for an enlarged prostate. The King is stepping back from public duties but carrying on state business during his treatment, which he'll receive as an outpatient, the palace said.

“The King has cancer,” the Times of London declared in a terse banner headline Tuesday. It was unlike any other in British history.

Never complain, never explain, as Charles' late mother, Queen Elizabeth II, was known to say. Charles has withheld details of his illness and treatment, and in that way is carrying on her approach. But in beaming a sliver of light from inside the palace walls and his own life, the King has broken with his mother and royal tradition.

A lot we still don't know

The world still does not know the cause of Elizabeth's death in 2022 at the age of 96. In the final years of her life, the public was told only that the queen was suffering from “mobility issues.” Her death certificate listed the cause simply as “old age.”

The British public wasn't told that Charles' grandfather, King George VI, had lung cancer before his death in February 1952 at the age of 56, and some historians have claimed that the King himself wasn't told he was terminally ill.

Given that Charles rules in a media-saturated age, “I do think it's incumbent on him to reveal more than he's revealed,” said Sally Bedell Smith, author of “Charles: The Passions and Paradoxes of an Improbable Life.”

“He was admirably candid in what he said about being treated for an enlarged prostate, and his impulse was to be open and also to encourage men to have the necessary examinations,” she added. “But then he reverted to the traditional royal form, which is mystery, secrecy, opacity.”

On Tuesday, former royal press secretary Simon Lewis told BBC Radio 4 that Charles' openness about his cancer diagnosis has been his style as a monarch.

“I think 20 years ago we would have got a very abrupt, short statement, and that's about it,” he said. The palace statement goes as far as possible, “given that the King has had a diagnosis of cancer and, as a lot of people know, processing that is a pretty tough process.”

One reason for disclosing his illness, the palace statement said, was “in the hope it may assist public understanding for all those around the world who are affected by cancer.” Cancer patient advocates reported glimmers of success on that front, with Cancer Research U.K. reporting a 42% rise in visits to its cancer information page, according to Dr. Julie Sharp, the group's head of health and patient information.

The jump “reflects that high-profile cancer cases often act as a prompt to encourage people to find out more or think about their own health,” she said.

But there was another pragmatic reason: To keep control of the information in the age of lightning-fast social media and misinformation. The palace statement said Charles “has chosen to share his diagnosis to prevent speculation.”

Leaders tend to hold information close

In the annals of power, leaders and their advisers strive to maintain - or at least, not undermine - the perception of being in strong and in control. Because to allow any perception of vulnerability or weakness could spark a fight for the gavel or the crown - or encourage a coup.

The former Soviet Union was famous for neglecting to mention when its leaders are sick or dead - think Leonid Brezhnev, Yuri Andropov and Konstantin Chernenko, secretly sick and soon deceased one after the other in the 1980s. Each event sparked scrambles for succession.

In the United States, there's little to no debate about the public's right to know the health status of their leaders. It's a key feature of the 2024 presidential rumble between President Joe Biden, 81, and former president Donald Trump, 77, with other contenders, such as GOP hopeful Nikki Haley, arguing that they're both too old to preside.

And on Feb. 1, Secretary of Defense Lloyd Austin - sixth in the presidential line of succession - apologized for keeping secret his cancer diagnosis and surgery. In a rare press conference, he acknowledged missing a key chance to use the experience as a teaching moment for those he leads across the Defense Department and, even more importantly, for Black Americans.

A right to know?

Whether the monarch owes the world more information about his health than other Britons do is a tense subject.

Royals are private citizens but also, in a sense, part of the public trust given that they are subsidized by British taxpayers and play an important - though largely powerless - constitutional role. Unelected, they inherit their wealth under a 1,000-year-old monarchy that Republican activists have long tried to dislodge.

And though some polls show the public is friendly toward Charles, opposition and apathy to the Monarchy are both growing. In a recent study by the National Centre for Social Research, just 29% of respondents thought the Monarchy was “very important” - the lowest level in the centre's 40 years of research on the subject. Opposition was highest among the young.

Remaining relevant is part of what makes Charles' legacy and succession so urgent. Maintaining at least the appearance of vitality can be key to leaders' pursuit of and hold on power. The King, the palace was careful to note, would step away from public-facing duties during his treatment but continue to manage other duties of state.

In Charles' case, succession has long been set: Next in line is his son, William, the Prince of Wales. But the King's illness makes William's preparation more critical at a time when he's also caring for his wife, Kate, Princess of Wales, who is recovering from abdominal surgery.

Charles' news was received with great sympathy in a country in which 3 million people live with cancer, according to Macmillan Cancer Support, a London-based charity. On average, it says, one person is diagnosed with cancer in the U.K. every 90 seconds. That's about 1,000 new cancer cases detected every day, according to the National Health Service.

That the King has joined those ranks - and, critically for a British monarch, shared that vulnerability with the world - heralded for some a new era of transparency in an era of social media and misinformation.