Buckingham Palace said in a statement on Monday that the monarch is receiving regular treatments for the condition, which was discovered after the 75-year-old underwent treatment for an enlarged prostate.
Officials have said that although Charles is stepping back from public-facing events, although he will continue to “undertake state business and official paperwork as usual”.
A Palace source told The Telegraph that Charles is a “little frustrated” by the impact the diagnosis has had on royal plans but is otherwise he is “in his usual good form”.
Charles called both Prince Harry and Prince William, as well as his siblings the Princess Royal, the Duke of York and the Duke of Edinburgh, to personally give them the news before it was publicly announced.
Since the diagnosis went public, here are the different ways members of the royal family have shown up to support Charles:
Prince Harry and Meghan Markle
Prince Harry cleared his diary and rushed back to the UK from his home in America on Tuesday to spend time with his father despite the rift between them.
The Duke of Sussex was seen arriving at a private terminal at Los Angeles in the morning before touching down at London’s Heathrow Airport at 12:20pm.
He was pictured back in the UK on Tuesday afternoon.
It is understood that Meghan has remained at the couple’s home with their children Archie and Lilibet.
Queen Camilla will continue with a full programme of public duties while her husband is treated, the Palace said.
She was seen walking side by side with the King at his last public appearance on Sunday, where the King waved to onlookers as he walked to church on the Sandringham estate in Norfolk.
Camilla has been a great support to Charles throughout his recent health battles. She visited the London Clinic several times over his stay in the private hospital when he underwent treatment for an enlarged prostate.
Princess Anne attended the first royal engagement since the revelation on Tuesday.
Known for her commitment to royal duties, Princess Anne went to an investiture ceremony on Tuesday morning. She was also scheduled to visit the Midlands on Tuesday on an official visit, but the event was cancelled.
Recipients at the ceremony included conductor Ivor Bolton, tenor Nicky Spence, rugby union referee Sara Cox and wheelchair rugby league player James Simpson.
When it was announced that Charles was due to undergo treatment for an enlarged prostate several weeks ago, Anne proved once again she was a reliable member of the family, taking on investiture ceremonies and continuing her royal visits.
Prince William and Princess Kate
While he has yet to make an appearance or statement since his father’s diagnosis was made public, the Prince of Wales is expected to shoulder some of Charles’ responsibilities.
He is set to return to official duties this week, in the aftermath of the Princess of Wales’s abdominal surgery which saw her recovering for 13 days in the same hospital her father-in-law was admitted to for his prostate procedure.
William will host an investiture ceremony at Windsor Castle on Wednesday and that evening will attend the London Air Ambulance annual fundraising gala in central London, Kensington Palace said.
Kate is not expected to return to royal duties until after Easter.
Prince Edward will also be returning to royal duties this week to support his brother.
Edward’s last public engagement was an overseas trip that finished on 26 January. The Duke of Edinburgh and his wife Sophie, both 59, are part of Charles’s slimmed-down working monarchy, introduced after his mother passed away last year.
Edward has two engagements scheduled on the royal diary this Thursday; attending a talent showcase at The Savoy in London as patron of the Production Guild of Great Britain and a reception at the Institute of Physics.
The King’s niece was also seen visiting him the morning after the diagnosis was made public.
Princess Beatrice was seen driving a Ranger Rover into the back entrance of Clarence House in London on Tuesday morning. She and her husband Edoardo Mozzi live next door to the King’s official royal residence at St James’s Palace.