The singer overcame the disease for a second time, all completely behind closed doors, before tragically discovering she had it for a third time previous year - when a tumour was found in her lower spine.
While Olivia beat her second bout of cancer, she is now battling the disease again, with a tumour past year found at the base of her spine.
Olivia revealed she was involved in a minor auto accident five years ago which led to the discovery of a lump on her back, and whilst she originally thought it was caused by the strain of her seatbelt during the collision, subsequent scans revealed the lump was actually the return of breast cancer.
Speaking to Sunday Night, the Hollywood star revealed how she had first thought the lump had been caused by the tension of her seatbelt, but scans showed it to be the return of a cancer she had beaten twenty years earlier.
Olivia was first diagnosed with breast cancer in 1992, which she overcame.
Olivia first noticed a lump in her shoulder back in 2013, following her involvement in a minor auto crash.
That time, the actress chose not to tell the public.
"I thought "I don't really need to share this, it's my life and something I wanted to keep to myself", she told reporter Alex Cullen.
When asked whether she was anxious about the cancer, she defiantly responded: "I believe I will win over it, and that's my goal".
"I'm very lucky that I live in a state where it's legal and that I have a husband that is a plant-medicine man", she says of spouse John Easterling, who grows cannabis on their California ranch. A lot of people see it as a fight and that is their prerogative.
But she has now told how she also fought the illness in secret in 2013. "And I'm doing really well".
"I live in this attractive place".
When asked if she was scared, she responded, "No, I don't go there". She also has a cancer centre named after her in Melbourne. I have all the animals that I adore.
Following her third diagnosis, the singer told Seven she was taking cannabis oil for the pain, a treatment she hoped would one day be available in her home country of Australia.