Olivia Newton-John reveals her breast cancer has returned

Grease actor has been forced to postpone her tour

She thought she was experiencing back pain but later discovered the disease had spread to her spine (REUTERS)

Olivia Newton-John has revealed her breast cancer has returned and she has been forced to postpone her June tour.

The singer, who recovered from her original diagnosis 25 years ago, said she initially thought she was experiencing back pain but later discovered the disease had spread to her spine.

The 68-year-old Australian, who played the lead role of Sandy in cult 1978 film Grease, said she would complete “a short course of photon radiation therapy” and hopes to return to the stage later in the year.

The four-time Grammy Award winner had been due to perform across America and Canada next month.

A statement on Tuesday said: “The back pain that initially caused her to postpone the first half of her concert tour, has turned out to be breast cancer that has metastasized to the sacrum.

“In addition to natural wellness therapies, Olivia will complete a short course of photon radiation therapy and is confident she will be back later in the year, better than ever, to celebrate her shows.

The musician herself added: "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”.

The statement said ticket buyers would be refunded for their purchases.

After recovering from her initial cancer diagnosis, Newton-John became a vocal campaigner for breast cancer research and other health issues. She is not only the spokesperson for a breast self-examination product Liv-Kit but also established the Olivia Newton-John Cancer and Wellness research centre in Melbourne in Australia.

The centre was partly subsidised by a sponsored walk along the Great Wall of China which was helped by high-profile friends such as Sir Cliff Richard and Joan Rivers.

After her role in Grease, Newton-John’s music career achieved success with the hit song "Physical" spending 10 weeks at the top of the Billboard charts in 1981. Billboard later bestowed it with the title of most popular song about sex in 2010.

Just last year, Newton-John weighed in on Grease's sequel which came out in 1982 but featured neither of its original stars, Newton-John or John Travolta.

When probed about how she felt about Grease 2, she succinctly said: “Not a lot”.

"I kind of remember they did ask us,” she continued. “I think they approached John [Travolta] and I to do it and then it didn't happen and I didn't think it was going to happen”.