Prince Philip had cancer for eight years before his death aged 99

It has been claimed that Prince Philip was diagnosed with cancer eight years before his death.

The then-Duke of Edinburgh passed away just two months before his birthday at Windsor Castle in April 2021.

A book by royal biographer Hugo Vickers, however, includes a detail about Philip's long-running illness, despite ‘old age’ being listed on his death certificate, the Daily Mail reports.

Titled Queen Elizabeth II, it claims Philip was first diagnosed with pancreatic cancer nearly eight years prior to his passing.

Two years after he was hospitalised in December 2011 for a blocked coronary artery, a private clinic in Marylebone was said to have detected a shadow on his pancreas.

They 'cut him right across his stomach' and 'the verdict was inoperable pancreatic cancer', according to the author.

Prince Philip died at Windsor Castle in April 2021 (Danny Lawson - WPA Pool/Getty Images)

Vickers wrote that on the night of his death, Philip poured himself a beer and drank it in the sitting room.

"The following morning, he got up, had a bath, said he did not feel well and quietly slipped away," he penned.

"By this point, he had lived with pancreatic cancer for nearly eight years – far longer than the usual survival time from diagnosis."

His wife, the Queen, was not with her husband of 73 years when he died, the author claims.

"As so often in life, he left without saying goodbye," Vickers wrote.

The NHS says pancreatic cancer 'is a cancer that's found anywhere in the pancreas'.

Queen Elizabeth II and Prince Philip had the longest marriage in royal history at 73 years (Jeff Spicer/Getty Images)

"The pancreas is an organ in the top part of your tummy. It helps you digest your food and makes hormones, such as insulin," the website reads.

"How serious pancreatic cancer is depends on where it is in the pancreas, how big it is, if it has spread and your general health."

There are around 10,200 pancreatic cancer deaths in the UK every year, that's 28 every day, according to Cancer Research UK.

At the time of the royal's death, his son and now-King Charles released an emotional message to his father.

"As you can imagine, my family and I miss my father enormously," the former Prince of Wales said.

"He was a much loved and appreciated figure and apart from anything else, I can imagine, he would be so deeply touched by the number of other people here and elsewhere around the world and the Commonwealth, who also I think, share our loss and our sorrow."

LADbible Group has contacted the royal family for comment.