LONDON, United Kingdom — King Charles III has written to Joe Biden expressing support after the former US president was diagnosed with an aggressive form of prostate cancer, Buckingham Palace said Monday.

Charles, who is undergoing treatment for an undisclosed form of cancer, sent a personal message to Biden over the weekend, offering best wishes following the announcement of the diagnosis.

Biden, 82, was diagnosed on Friday with a Gleason score of nine, indicating a highly aggressive form of the disease, according to a statement released by his office.

The cancer has reportedly spread to his bones but remains hormone-sensitive, enabling treatment options.

“While this represents a more aggressive form of the disease, the cancer appears to be hormone-sensitive, which allows for effective management,” the statement said.

On Monday, Biden posted on social media for the first time since the announcement, thanking the public for their messages of support.

“Cancer touches us all,” he wrote.

“Like so many of you, Jill and I have learned that we are strongest in the broken places. Thank you for lifting us up with love and support.”

The two leaders have met several times in recent years. Biden visited Britain for Queen Elizabeth II’s funeral in 2022 and held bilateral talks with Charles — then Prince of Wales — during the COP26 climate summit in Glasgow in 2021.

In July 2023, Biden had tea with the king at Windsor Castle, with a palace spokesperson describing the meeting as “extremely cordial.”

Biden had previously expressed concern following Charles’ own cancer diagnosis in 2024.

“I’m concerned about him. Just heard about his diagnosis. I’ll be talking to him, God willing,” Biden told reporters at the time.

He later posted on social media: “Navigating a cancer diagnosis, treatment, and survivorship takes hope and absolute courage.”

The king last week gave a rare public comment about his health, telling a former patient during a visit to Bradford that he hoped to be on the “better side” of his treatment.

Prostate cancer is the most common cancer among men in the United States and the UK.

The Gleason score is used to assess the severity, with higher scores indicating more aggressive disease.