Former US President Joe Biden is undergoing radiation therapy for an aggressive form of prostate cancer diagnosed in May.

"As part of a treatment plan for prostate cancer, President Biden is currently undergoing radiation therapy and hormone treatment," his spokesperson said on Saturday.

Biden, who turns 83 next month, underwent a procedure known as Mohs surgery in September to remove cancerous cells from his skin.

Following that procedure, his physician wrote in a memo that "all cancerous tissue was successfully removed" and that no further treatment was required.

Biden's prostate cancer diagnosis revealed this May

The Democratic former president revealed in May that he had been diagnosed with prostate cancer that had metastasized to the bone.

Biden's office said in a statement at that time that his cancer appeared to be "hormone-sensitive which allows for effective management."

That meant that he was likely to respond to treatment. NBC News reported that the radiation treatment is expected to last five weeks and marked a new stage in his care.

He had already been taking a pill form of hormone medication and is said to be "doing well."

Edited by: Saim Dušan Inayatullah