TAMPA, Fla. (WFLA) — Olivia Newton-John passed away at her ranch in Southern California Monday at the age of 73, according to a message from her husband.

The singer, songwriter, actress, entrepreneur and activist passed away peacefully at her ranch surrounded by family and friends.

“Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer,” a message posted to her Facebook page said.

In 2017, the singer, who was 68-year-old at the time, announced her battle with breast cancer. Newton-John said she initially thought she was suffering from back pain, but later learned it was “breast cancer that has metastasized to the sacrum.”

According to the Associated Press, Newton-John was involved in several charitable causes and served as a goodwill ambassador for the United Nations Environment Programme and as a national spokeswoman for the Children’s Health Environmental Coalition. She also founded the Olivia Newton-John Cancer and Wellness Centre in Melbourne, Australia.

Newton-John also served on the board of advisors for the Moffitt Cancer Center in Tampa to “contribute to the prevention and cure of cancer.”

“Her healing inspiration and pioneering experience with plant medicine continues with the Olivia Newton-John Foundation Fund, dedicated to researching plant medicine and cancer.”

Newton-John was a four-time Grammy Award-winning singer who had five number-one hits and 10 top-ten hits on the Billboard Hot 100.

As an actress, Newton-John was most well-known for playing Sandy Olsson in the 1978 movie “Grease.” Her co-star John Travolta, who played Danny Zuko, paid tribute to his friend on Instagram Monday evening.

“My dearest Olivia, you made all of our lives so much better. Your impact was incredible. I love you so much. We will see you down the road and we will all be together again,” Travolta wrote. “Yours from the first moment I saw you and forever! Your Danny, your John!”

In lieu of flowers, the family asked that any donations be made in her memory to the Olivia Newton-John Foundation Fund.

Olivia is survived by her husband John Easterling; daughter Chloe Lattanzi; sister Sarah Newton-John; brother Toby Newton-John; nieces and nephews Tottie, Fiona and Brett Goldsmith; Emerson, Charlie, Zac, Jeremy, Randall, and Pierz Newton-John; Jude Newton-Stock, Layla Lee; Kira and Tasha Edelstein; and Brin and Valerie Hall.

Family members asked fans to respect the family’s privacy during this “very difficult time.”