EXCLUSIVE: Olivia Newton-John on Her Battle With Breast Cancer, In Her Own Words

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Olivia Newton-John announced on Tuesday that she was reluctantly postponing her June tour dates after her breast cancer metastasized to the sacrum, but this isn't the first time she has fought the disease. The 68-year-old singer underwent a mastectomy after she was originally diagnosed with breast cancer in 1992.

RELATED: Olivia Newton-John Reveals Her Breast Cancer Has Spread, Postpones Concert Dates

"Breast cancer is a very scary thing to go through and particularly in the first initial stages when you are first diagnosed because you don't know what that means. You don't know if it's spread anywhere else in your body. You don't know if you're gonna die. You don't know anything," she told ET during a sit-down interview in 2005. "And I guess the first few days after you go through shock and disbelief and common things that you go through, denial, there's a lot of fear."

"I also was determined that I was gonna get through it, but I'd be lying if I said I didn't have fear and dread," she continued. "Of course I did."

Newton-John's battle with breast cancer inspired her 2005 album, Stronger Than Before.

"Whatever you go through, pain makes you grow even though it's difficult at the time," she told ET.

WATCH: Olivia Newton-John on Reports That Her Long-Missing Boyfriend Faked His Death: 'Nobody Knows What Really Happened'

"Initially when I was first diagnosed for me it was a very private matter, that's why I was laughing when I was sitting here talking about my breasts so openly, because when I was first diagnosed that was the last thing in the world I wanted to talk about, and I was so nervous about people finding out about it," she recalled, explaining that finally being able to share her story was "a very positive thing for me."

"I think it's an individual journey for everybody. For me, it was good to talk about it," she added.

By 2012, Newton-John had become an advocate for health awareness, and opened a cancer and wellness center near Melbourne, Australia. The same center is now helping her current treatment. "I decided on my direction of therapies after consultation with my doctors and natural therapists and the medical team at my Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia," she said in a statement on Tuesday.

In 2013, Newton-John also started a brain tumor fund in honor of her sister, Rona, who died just six weeks after being diagnosed with the disease.

RELATED: Olivia Newton-John's Sister Rona Dies

"It was very, very fast, yes," she told ET in 2014. "We never know when it's our time. All I can say is that she had all the people she loved around her and it was a beautiful time."

"There was a time where I didn't think I'd sing again, but time is a wonderful healer and it doesn't heal everything, but singing for me is my way of healing and it always has been," she shared of her return to music after Rona's death. "Whenever I've gone through difficult times in my life, music is what has helped me get through. She was always there for me, so I know that I need to keep singing, she didn't want me to stop."

As far as her own battle with cancer, Newton-John told ET in 2007 that "there was no question that I was going to get over it."

"I don't like the word remission. I've always said, 'No, it's gone,' because I think that's also an emotional thing that you keep in the back of your mind. Remission sounds like it's lurking over your shoulder," she confessed.

EXCLUSIVE: Olivia Newton-John and Daughter Chloe Lattanzi Pay Tribute to 'Xanadu' in Trippy New Video

"I feel so blessed in every aspect of my life and there's no way it was going to get me," she said. "My daughter [Chloe Lattanzi] is everything to me, and for her, I want to be here more than anything. But life itself, too, is an incredible gift, so those two things, there's no way."

Newton-John recently collaborated with her daughter in the studio. See more in the video below.