Olivia Newton-John has been forced to postpone her Las Vegas Residency to help her ill sister, Rona, who has been diagnosed with brain cancer.

While no dates had been announced, it was known that she would be playing the Flamingo with dates in the spring and summer in place of Donnie and Marie Osmond who were reducing their Las Vegas commitment.

Olivia is the youngest of the her family with brother Hugh the oldest and Rona in the middle. Rona has acted in the past and was once married to the late-actor Jeff Conaway.

Newton-John posted the following on her website:

"I recently received the very sad news that my beautiful sister, Rona Newton-John, has been diagnosed with brain cancer. In light of this news, I have decided to postpone my forthcoming Las Vegas residency to spend time with her and our family.

"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.

" I want to thank everyone in advance for respecting our privacy during this difficult time."

- Olivia

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