The Biden office said at the time that “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 meant his illness was classified as “high-grade” and the cancer cells could spread quickly, according to Cancer Research UK.
A person close to Biden has said the former president is doing well and responding to treatment, the BBC’s US news partner CBS reported, with another source telling the outlet that the radiation started “a few weeks ago” in Philadelphia.
Biden 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.
His former Vice-President, Kamala Harris, ran instead as the Democrats’ presidential candidate, losing to current US President Donald Trump.
For many years, Biden has advocated for cancer research.
In 2022, he and his wife Jill 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 lost his eldest son, Beau, to brain cancer in 2015.
The former president and vice-president has also been treated twice for skin cancer, in 2023 and 2025.
In recent months, Biden has largely retreated from the public eye.
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”.
Prostate cancer is the second most common cancer affecting men, behind skin cancer, according to the American Cancer Society.
The US Centers for Disease Control and Prevention (CDC) says that 13 out of every 100 men will develop prostate cancer at some point in their lives. It says age is the most common risk factor.
