Olivia Newton-John, a four-time Grammy winner and actor in the immensely popular musical Grease, had disclosed several years ago that breast cancer had metastasized and spread to her back, forcing her to cancel performances. The singer, who soared to the top of the world's pop music charts in the 1970s and 1980s, died on Monday (August 8) at the ripe old age of 73 at her home in southern California.

Twenty-five years earlier Newton-John had undergone a partial mastectomy and gone on to establish a cancer treatment-research facility in Australia. The entertainer began performing as a child and became a global superstar after moving to the United States. She had her first hit in 1971 with 'If Not for You' - a Bob Dylan song that also had been recorded by George Harrison.

It would be followed in the next few years by 'Let Me Be There', which won her a Grammy for best female country vocal performance, 'If You Love Me (Let Me Know)' and two No. 1 songs, 'Have You Never Been Mellow' and 'I Honestly Love You'. The latter song won Grammys for best female pop performance and record of the year.

She also cemented a place for herself in Hollywood by co-starring with John Travolta in the 1978 film that would become one of the most popular musicals in Hollywood history, Grease. In the film, Newton-John played the female lead Sandy who has a summer fling with Danny, the greaser portrayed by Travolta. She would make another movie with Travolta, Two of a Kind in 1983, and they recorded an album of Christmas songs in 2012.

The 1978 film wowed critics and audiences, and its soundtrack generated a string of hits, including the title song, Newton-John's 'Hopelessly Devoted to You', 'Summer Nights', and her bouncy duet with Travolta, 'You're the One That I Want'.

In 1981 Newton-John scored her biggest hit single, 'Physical'. The song's accompanying video featured her in workout clothes and a headband, which fueled a fashion trend. Its sex-infused lyrics eroded her good-girl image and led some radio stations to ban it. Later in 2015, she had another No. 1 hit on the dance charts - 'You Have to Believe', a revamped version of 'Magic' performed with her only child, Chloe Lattanzi.