Former US President Joe Biden, 82, has been diagnosed with prostate cancer that has spread to his bones, a statement from his office said on Sunday.

The discovery was made on Friday after he reported urinary symptoms which led doctors to find a small nodule on his prostate.

The cancer is a more aggressive form of the disease and Biden and his family are reviewing treatment options, the statement said.

He left office in January as the oldest serving US president in history and questions about his health dogged his first term, leading him to end his run for re-election late in his campaign.

In Sunday's statement, Biden's office said: "Last week, President Joe Biden was seen for a new finding of a prostate nodule after experiencing increasing urinary symptoms.

"On Friday, he was diagnosed with prostate cancer, characterised by a Gleason score of 9 (Grade Group 5) with metastasis to the bone.

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

A Gleason score of nine means his illness is classified as "high-grade" and the cancer cells could spread quickly, according to Cancer Research UK.

After news broke of his diagnosis, the former president received support from both sides of the aisle.

President Donald Trump wrote on his social media platform Truth Social that he and First Lady Melania Trump were "saddened to hear about Joe Biden's recent medical diagnosis".

"We extend our warmest and best wishes to Jill and the family," he said, referring to former First Lady Jill Biden. "We wish Joe a fast and successful recovery."

Former Vice-President Kamala Harris, who served under Biden, wrote on X that she and her husband Doug Emhoff are keeping the Biden family in their prayers.

"Joe is a fighter – and I know he will face this challenge with the same strength, resilience, and optimism that have always defined his life and leadership," Harris said.

In a post on X, Barack Obama – who served as president from 2009 to 2017 with Joe Biden as his deputy – said that he and his wife Michelle were "thinking of the entire Biden family".

"Nobody has done more to find breakthrough treatments for cancer in all its forms than Joe, and I am certain he will fight this challenge with his trademark resolve and grace. We pray for a fast and full recovery," Obama said. In 2016, Obama tasked Biden with leading a "cancer moonshot" government-wide research programme.

In the UK, Prime Minister Keir Starmer said: "I am very sorry to hear President Biden has prostate cancer. All the very best to Joe, his wife Jill and their family, and wishing the president swift and successful treatment."

The news comes nearly a year after the former president was forced to drop out of the 2024 US presidential election over concerns about his health and age.

Biden, then the Democratic nominee vying for re-election, faced mounting criticism of his poor performance in a June televised debate against Republican nominee and current president Donald Trump.

He was replaced as the Democratic candidate by his vice-president, Kamala Harris.

Trump, 78, became the oldest person to take the oath when he took over from Biden.

Prostate cancer is the second most common cancer affecting men, behind skin cancer, according to the Cleveland Clinic. The US Centres for Disease Control and Prevention (CDC) says that 13 out of every 100 men will develop prostate cancer at some point in their lives.

Age is the most common risk factor, the CDC says.

Dr William Dahut, the Chief Scientific Officer at the American Cancer Society and a trained prostate cancer physician, told the BBC that the cancer is more aggressive in nature, based on the publicly-available information on Biden's diagnosis.

"In general, if cancer has spread to the bones, we don't think it is considered a curable cancer," Dr Dahut said.

He noted, however, that most patients tend to respond well to initial treatment, "and people can live many years with the diagnosis".

Dr Dahut said that someone with the former president's diagnosis will likely be offered hormonal therapies to mitigate symptoms and to slow the growth of cancerous cells.

Biden had largely retreated from the public eye since leaving the White House and he has made few public appearances.

In May, he sat down for an interview with the BBC - his first since leaving the White House - where he admitted that the decision to step down from the 2024 race was "difficult".

Biden has faced questions about the status of his health in recent months.

In an appearance on The View programme that also took place in May, Biden denied claims that he had been experiencing cognitive decline in his final year at the White House. "There is nothing to sustain that," he said.

For many years, the president had advocated for cancer research.

In 2022, he and Mrs Biden relaunched the "cancer moonshot" initiative with the goal of mobilising research efforts to prevent more than four million cancer deaths by the year 2047.

Biden himself lost his eldest son, Beau, to brain cancer in 2015.