The party leader will take a step back from politics following the diagnosis.

The 58-year-old confirmed he has been diagnosed with throat cancer on the Today with Claire Byrne show, saying: "I wanted to take the opportunity to say I recently got a cancer diagnosis and I found out a few weeks ago.

"And I have to enter into a fairly intense period of cancer treatment over the next … well, it's going to certainly take a couple of months probably.

"All in all, we could be talking three or four months."

The People Before Profit leader said he would be stepping back from politics during his treatment.

"I wanted to explain it because if I just disappeared, people, the constituents who elected me, would be wondering where I'm gone, so I wanted to do them the service of telling them.

"The people who voted for People Before Profit deserve to know if I'm not around and I just want to stress, I plan to be back as soon as possible," he added.

Mr Boyd Barrett shared that while shaving during the General Election campaign last year, he noticed swelling in his neck.

"They suspected that it was cancer - they had to do an operation, a biopsy, I ended up having to get my tonsils taken out and they found that I had throat cancer that was prompted by the HPV virus."

He explained that doctors think it is likely he picked up the virus years ago.

HPV can be activated because of age, stress, or a weakened immune system.

"According to the doctors, when it's virus-induced, it does improve your chances of recovery.

"The doctors have said that it is very curable - so I have a good chance.

"It's been caught relatively early because it was in my tonsils, it's gone to my lymph nodes but no further, so I have to get radio[therapy] and chemotherapy, and they say the chances of that working are about eight or nine out of ten, which is good," he continued.

"But obviously you could be unlucky, and be the one in ten or the two in ten that it doesn't work for, so you have to throw everything at it."

Mr Boyd Barrett's Dún Laoghaire office will remain open, with retired People Before Profit TD Bríd Smith assisting in its operation.