Donald Trump jr has been accused of going too far with social media posts fuelling conspiracy over former US President Joe Biden’s cancer diagnosis.

It was revealed on Monday (AEST) that Biden has been diagnosed with an “aggressive form” of prostate cancer that has spread to his bones.

Biden, 82, was diagnosed on Friday after experiencing urinary symptoms, and he and his family are reviewing treatment options with doctors, according to a statement.

“Cancer touches us all. Like so many of you, Jill and I have learned that we are strongest in the broken places,” Biden posted late on Monday (AEST).

“Thank you for lifting us up with love and support.”

US President Donald Trump expressed sympathy for Biden and Jill, writing: “We extend our warmest and best wishes to Jill and the family, and we wish Joe a fast and successful recovery.”

However, Trump’s eldest son, Donald Trump jr, has been accused of insensitivity for pushing MAGA conspiracy theories about a cancer cover-up.

After initially appearing to wish the Bidens well, Trump jr followed up with comments claiming Biden would have been cancerous during his time in office.

He posted a screenshot of a doctor’s claim that prostate cancer evolves over five to seven years, which meant that Biden would have had the cancer throughout his White House tenure.

“What I want to know is how did Dr. Jill Biden miss stage five metastatic cancer or is this yet another coverup???,” Trump jr wrote on Tuesday (AEST).

He also posted an old video of Biden when he was president saying he had cancer.

“Joe says he had cancer 2 years ago & everyone said it’s a gaffe. When he clearly had dementia, everyone said he’s lucid,” wrote Trump jr.

“Now that he’s no longer useful they’re all shocked that they missed it. Everyone was in on the cover-up!

“Who was running the country? We need accountability!”

In another post Trump jr wrote: “The Dem-Media is trying to cover up the cover up over Biden’s failing health. Which was obvious to anyone with a functioning brain. Because they know it implicates all of them.”

Doctors query diagnosis

Biden’s cancer announcement has revived questions about the extent of his health issues during his tenure.

Several doctors said cancers like this were typically diagnosed before were so advanced.

“I would assume the former president gets a very thorough physical every year,” said Dr Chris George, medical director of the cancer program at Northwestern Health Network.

“It’s sort of hard for me to believe that he’s had a [blood test] within the past year that was normal.”

Dr Herbert Lepor, a urologist at NYU Langone Health, said that given the available screening options, “it is a bit unusual in the modern era to detect cancers at this late stage”.

About 70 per cent of prostate cancer cases were diagnosed before they spread to other organs, according to the Centres for Disease Control and Prevention.

US guidelines do not recommend annual blood screening for men over 70 and it is unclear whether the annual presidential exam would have included those tests.

Vice President JD Vance said Biden should have been more transparent with the public.

“Why didn’t the American people have a better sense of his health picture? Why didn’t the American people have more accurate information about what he was actually dealing with? This is serious stuff,” Vance said as he wrapped up a trip to Rome.

He wished Biden “the right recovery”.

The remarks by Vance, a Republican, captured the renewed focus on Biden’s health with the publication of a book that details widespread concerns about his mental acuity among aides and Democratic insiders as he pursued re-election in 2024.

Excerpts from the book have prompted questions about whether critical information was withheld from the US public about Biden’s ability to serve in the White House.

Biden’s closest aides have dismissed those concerns, saying Biden was fully capable of making important decisions.

Biden has appeared on television to reject accusations that his mental capacity had diminished during his 2021-2025 term.

“There’s nothing to sustain that,” he said on ABC’s The View on May 8.

Biden, the oldest person to serve as US president, was forced to drop his re-election bid last July after a stumbling debate performance against Republican rival Donald Trump eroded his support among fellow Democrats.

Biden’s vice president, Kamala Harris, launched a bid of her own but lost to Trump in the November 2024 election.

A new book, Original Sin, by journalists Jake Tapper and Alex Thompson put a spotlight on Biden’s mental acuity in his final months in office.

“It was a mistake for Democrats to not listen to the voters earlier,” US Senator Chris Murphy of Connecticut, a potential 2028 Democratic presidential candidate, said on NBC on Sunday.

Biden faced no serious challenge for the 2024 Democratic nomination, and party leaders repeatedly vouched for his ability to serve a second four-year term even though a Reuters/Ipsos poll suggested 74 per cent of voters in January 2024 thought he was too old for the job.

Biden’s cancer diagnosis drew an outpouring of sympathy from supporters and rivals alike, including Trump.

-with AAP/PA