It was just a week ago that King Charles III walked out of a private hospital in London following treatment for a benign prostate condition.
Now he's fighting an undisclosed form of cancer separate from his initial diagnosis that puts a cloud of uncertainty over his future health less than 18 months into his reign.
The statement from Buckingham Palace suggests King Charles remains upbeat about his prospects for a full recovery.
His treatment has begun already and there are suggestions doctors have identified the problem relatively early.
But the UK is a country that is used to its royals being in rude health.
It grew up with Queen Elizabeth II, a monarch who rode horses into her 90s, sat on the throne for more than 70 years, and had a husband who lived to 99 and a mother who made it to 102.
The king is 75, has had a lifetime of mostly good health and has kept active through playing sport and walking.
However, the nation will be worried about his prognosis.
A slimmed-down monarchy
He will continue to carry out his duties — processing state documents and meeting regularly with the prime minister — but "public-facing" duties will be postponed.
That means it's unlikely he will be seen in public on a regular basis for a while and that will invariably lead to speculation about his treatment and his health.
King Charles made a promise to slim down the monarchy when he became king in September 2022.
Some of that has been by design, some of it has not.
His second son Prince Harry stepped away from the royal family, moving to the US with his wife and children in 2020 and away from the attention of the prying British tabloid media he loathes so much.
His brother Prince Andrew will not return to public duties. He had his military titles stripped following the case brought against him by Virginia Giuffre, who was linked to the royal's former friend, the convicted paedophile and sex-trafficker Jeffrey Epstein.
His son, Prince William, the heir to the throne, suddenly has other priorities. He's been looking after his wife Catherine, who is convalescing after abdominal surgery and 13 nights in hospital.
William and Catherine are the only working royals on the payroll below the age of 50. The Princess of Wales is not due to return to public duties until after Easter.
There will be pressure on Prince William to step up and fill the breach.
On the day of his father's diagnosis, it was announced he was returning to work this week to conduct an investiture at Windsor Castle and attend a fundraiser in London.
However, it was described as only a "partial return to work". There may soon be pressure on him to accelerate his return to full-time duties and add a few of his father's responsibilities to the mix.
Uncertainty over Australia visit and Commonwealth meeting
It was expected that the king would this year travel to Australia, New Zealand and Canada. It was also suggested he would prioritise making it to the Commonwealth Heads of Government Meeting (CHOGM) in Samoa in October.
The Commonwealth was incredibly important to the king's mother. And he has spoken lovingly about the Queen's devotion to service, renewing his own "promise of lifelong service" in tribute to her.
In her final years, Queen Elizabeth was unable to make the long-haul trips to Commonwealth countries that meant so much to her.
The king will be desperately keen to make these trips if his health allows and restart all of his public duties in the UK as soon as possible.
Given how much his mother's legacy means to him, any absence from these public duties will be noted and lead to speculation about the king's health and his treatment.
Buckingham Palace insists the king will be able to fulfil his constitutional role — including giving royal assent to parliamentary bills, opening new sessions of parliament and appointing new prime ministers and ministers — something that has been a frequent duty for the monarch in the UK in recent years.
The palace has sought to assure the public there will be no constitutional crisis.
If the king can't step up to fulfil those duties due to ill health, Queen Camilla, Prince William, Anne, the Princess Royal, and Prince Edward all have the legal power to step in.
For King Charles, the next few months are likely to be a time of private recuperation and public speculation.