David Norris, who revealed he was diagnosed with cancer back in June, has said he may need a liver transplant.
The Independent Senator has revealed his doctors have succeeded in "considerably" reducing the size of the main tumor on his liver.
However, the 69-year-old said his cancer is 'inoperable' and can't be removed by surgery. His medical team at St Vincent's Private Hospital in Dublin have said a liver transplant may be his best hope of recovery.
He said: "It's an inoperable cancer, it's a tumor on the liver.
"It's related to the fact I had [viral] hepatitis 20 years ago and with all the stress I had in the past couple of years, it's come back as cancer.
"But I've a wonderful team at St Vincent's. They're using this new technology, where they inject poison directly into the tumor.
"I had a very big dose of it about six weeks ago and I've just got the results and they say that the main tumor has retracted very considerably and some of the small ones have gone. So I may be in line for a liver transplant."
During an interview on The Ray D'Arcy show on Today FM, Norris said he was felt very "optimistic and positive" about the future.
The former presidential candidate said he felt energized about the upcoming referendum on the abolition of the Senate.
He claims the country would be in a dangerous position if the Senate was abolished.
He said: "The Senate is different to the Dail. We bring expertise to refine legislation.
"There were nearly 600 amendments made in the last 18 months."