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, although specifics have not been disclosed.

The radiation treatment is expected to last five weeks, representing a new phase in his care, a source informed NBC News.

In May, Biden's office disclosed that he was diagnosed with a more aggressive form of the disease, characterized by a Gleason score of 9 (Grade Group 5) and metastasis to his bones. This diagnosis followed his reporting of urinary symptoms, which led to the discovery of a small nodule on his prostate.

The Biden administration noted, at the time, that while the cancer represents a serious form, it appears to be hormone-sensitive, allowing for effective management.

A Gleason score of nine indicates a high-grade cancer, with cells that can spread rapidly, according to Cancer Research UK.

Biden left office in January as the oldest serving US president, and concerns regarding his health were prevalent during his first term. He subsequently opted to end his run for re-election later in his campaign.

His former vice president, Kamala Harris, took over as the Democrat's presidential candidate but was ultimately defeated by current US President Donald Trump.

Throughout his career, Biden has been a strong proponent for cancer research. In 2022, he and First Lady Jill Biden relaunched the cancer moonshot initiative aimed at mobilizing research efforts to prevent over four million cancer deaths by 2047.

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

In recent months, Biden has limited his public appearances. In May, he participated in an interview with the BBC, during which he acknowledged the difficulty of his decision to withdraw from the 2024 presidential race.

According to the American Cancer Society, prostate cancer is the second most common cancer among men, following skin cancer. The US Centers for Disease Control and Prevention (CDC) states that 13 out of every 100 men will face a prostate cancer diagnosis in their lifetime, with age as the primary risk factor.