Olivia Newton-John has revealed that her sister Rona has died of an aggresive brain tumour.
The Australian confirmed the sad news on Wednesday by posting a loving tribute to sister Rona, 70, on her Facebook account.
Accompanied by a beautiful picture of Rona, she wrote: "My beautiful sister Rona sadly passed on May 24th in Los Angeles. It was May 25th in Australia - which was our mother Irene's birthday. Rona died of a very aggressive brain tumour and mercifully suffered no pain.
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She added: "She was surrounded by the love of her four children - Fiona, Brett, Tottie and Emerson and, her wonderful friends. I will miss her forever - my beautiful, smart, talented, funny, brave sister Rona."
Olivia, 64, has asked that in lieu of flowers all donations be made to the ONJCWC, the Olivia Newton-John Cancer & Wellness Centre at the Austin Hospital in Heidelberg, Melbourne, Australia, where a brain tumour wellness programme will be started in Rona's name.
In recent months, the Grease star had cancelled concerts to care for her sick sister. Olivia confirmed the "very sad" news of Rona's illness in a statement to Entertainment Tonight in April. "In light of this news, I have decided to postpone my forthcoming Las Vegas residency to spend time with her and our family," the star wrote.
"As a cancer 'thriver' myself, as many people are, I am very aware of the importance of love, support and family during this journey she is about to begin."
Rona Newton-John was also an actress. She was married to Olivia's Grease co-star Jeff Conaway – Kenickie in the classic film – for five years. The couple had one son together, Emerson, now 38.