Speaking to NOVA's Fitzy & Wippa, the 29-year-old revealed that if he didn't go to hospital as soon as he did, he could have died.
There was also a chance he could have died during his operation.
"I spoke to the neurosurgeon that did the operation… he said to me look, you know, if you hadn’t come in when you did you would’ve died that night," Ruffo told the radio hosts.
"You would’ve had a brain aneurism and not woken up at all.”
Speaking about the size of the tumour, Ruffo revealed that his neurosurgeon said the tumour could have been growing for two to 10 years.
To get rid of the remaining 5% of the tumour, the actor and singer needs to go through radiotherapy, which he is currently undergoing.
He will then start chemotherapy for six months, and although his doctors can't give a definitive answer, they are hopeful for a positive outcome.
Listen to his full interview below.