Former US President Joe Biden is receiving radiation therapy as part of his treatment for prostate cancer, his spokesman has said.

The spokesman also stated that Biden, 82, is undergoing hormone treatment, without providing further details.

The radiation treatment is expected to span five weeks and marks a new point in his care, according to NBC News.

In May, Biden's office announced that he was diagnosed with a more aggressive form of the disease that had spread to his bones. The discovery was made after Biden reported urinary symptoms which led doctors to identify a small nodule on his prostate.

At that time, the Biden office revealed he was diagnosed with prostate cancer, characterized by a Gleason score of 9 (Grade Group 5) with metastasis to the bone. While this represents a more aggressive form of cancer, it appears to be hormone-sensitive, allowing for effective management.

A Gleason score of nine signifies a "high-grade" illness with potential rapid spread of cancer cells, according to Cancer Research UK.

Biden left office in January as the oldest serving US president in history, and health concerns plagued his first term, culminating in his decision to withdraw from re-election late in his campaign.

His former vice-president, Kamala Harris, eventually ran as the Democrat's presidential candidate, losing to current US President Donald Trump.

Biden has been a strong advocate for cancer research over the years, and in 2022, he and his wife Jill Biden relaunched the cancer moonshot initiative, aimed at mobilizing research efforts to prevent over four million cancer deaths by 2047.

Biden himself faced personal loss when he lost his eldest son, Beau, to brain cancer in 2015.

In recent months, Biden has largely retreated from the public eye. He sat down for a BBC interview in May—the first since leaving the White House—where he admitted that stepping down from the 2024 race was a difficult decision.

Prostate cancer is the second most common cancer among men, following skin cancer, as reported by the American Cancer Society. The US Centers for Disease Control and Prevention (CDC) states that one out of every eight men will develop prostate cancer at some point in their lives, with age being the most common risk factor.