King Charles shared his diagnosis to prevent speculation and hoping to ‘assist public understanding for all those … affected by cancer’, said the palace. Photograph: Andy Rain/EPA

King Charles III

Monarch has started schedule of treatments after diagnosis made recently when he was treated for benign enlarged prostate

King Charles diagnosed with cancer, Buckingham Palace announces

Monarch has started schedule of treatments after diagnosis made recently when he was treated for benign enlarged prostate

King Charles diagnosed with cancer 

King Charles has been diagnosed with cancer, Buckingham Palace has announced.

The diagnosis was made recently while the monarch, 75, had treatment at the London Clinic for a benign enlarged prostate.

In a statement, Buckingham Palace said: “During the king’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted. Subsequent diagnostic tests have identified a form of cancer. His majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties.

“Throughout this period, his majesty will continue to undertake state business and official paperwork as usual. The king is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure. He remains wholly positive about his treatment and looks forward to returning to full public duty as soon as possible.

“His majesty 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.”

Buckingham Palace was not releasing any further details at this stage.

The king is understood to have personally informed his sons, William and Harry, and his three siblings – the Princess Royal, Duke of Edinburgh and Duke of York – of his diagnosis.

The Duke of Sussex had spoken to the king about his cancer diagnosis and would be travelling to the UK to see him in the coming days, a source close to Harry said.

“The duke did speak with his father about his diagnosis. He will be travelling to the UK to see his majesty in the coming days,” the source added.

It is understood that the diagnosis is not of prostate cancer, in light of his separate diagnosis of benign prostate enlargement.

The king is understood to have returned to London from Sandringham on Monday morning to begin treatment as an outpatient.

King Charles III and Queen Camilla arriving to attend a Sunday church service at St Mary Magdalene church in Sandringham on Sunday. Photograph: Joe Giddens/PA

The king was last seen in public at Sandringham on Sunday to attend a church service with the queen, which was the first time he had been seen since he was discharged from the London Clinic.

He smiled and waved to wellwishers as he walked to St Mary Magdalene church in Sandringham, Norfolk.

The announcement brought a stream of messages from wellwishers.

The prime minister, Rishi Sunak, reacted to the news by tweeting: “Wishing his majesty a full and speedy recovery. I have no doubt he’ll be back to full strength in no time and I know the whole country will be wishing him well.”

The Labour leader, Keir Starmer, wished the king “all the very best for his recovery”.

He tweeted: “On behalf of the Labour party, I wish his majesty all the very best for his recovery. We look forward to seeing him back to swift full health.”

The Commons speaker, Sir Lindsay Hoyle, told MPs: “I know the whole house will wish to join me in expressing our sympathies with his majesty the king following the news announcement this evening.

“Our thoughts are, of course, with his majesty and his family, and we’d all wish to send him our very best wishes for the successful treatment and a speedy recovery following tonight’s news.”

The king is postponing public-facing duties while undergoing treatment at the same time as the Princess of Wales also postpones her public engagements while recuperating from the abdominal surgery she underwent, also at the London Clinic.

Catherine, Princess of Wales, had determined to keep her medical details private. But with her also out of action – she is not expected to return to public duties until after Easter – it presents problems for the monarchy, which is significantly diminished in the number of working royals because of the departure of the Duke and Duchess of Sussex.

Kensington Palace announced earlier on Monday that the Prince of Wales, who took time off while his wife was in hospital, would resume public duties this week by conducting an investiture on Wednesday at Windsor Castle, followed by a gala fundraising event for the London Air Ambulance in the evening.

The king has largely enjoyed good health throughout his life. The first signs of any significant concern came with Buckingham Palace’s surprise announcement on 17 January that he had sought treatment for an enlarged prostate.

The palace stressed that his condition was benign and that he would attend hospital the following week for a corrective procedure.

He was said to be personally keen to share details of his benign prostate diagnosis to encourage other men who may be experiencing symptoms to get themselves checked.