The 46-year-old coach on The Voice spoke to Karl Stefanovic about her dark days fighting the disease.
"Someone said to me at the time be a little bit selfish but it's not in my nature to be selfish, but now was the time to do that, to let people take care of you and that’s what I did," she said.
"I know I have strength but when you are fighting something where there are a lot of unknowns there’s a mixture, mixture of emotions and memories.
"It is years until you really get the all-clear and by the time my hair starting growing back it was very exciting; it was like a miracle."
The pop princess, who is going on a national tour next year, also revealed details about her relationship with INXS star Michael Hutchence in the '80s.
"It was great love and it was true heartbreak," the singer said.