Grease may have catapulted Dame Olivia Newton-John to fame, but her campaigning around breast cancer will be just as central to her legacy.

The 73-year-old “passed away peacefully” in Southern California on Monday surrounded by friends and family, her widower John Easterling said in a short statement.

She was first diagnosed with breast cancer in 1992, which returned in 2013 in her shoulder and again in 2017, this time in her spine.

Her lengthy experience with the illness saw her become a fierce advocate for cancer awareness.

The Grammy Award-winning singer, who starred as Sandy in the hit musical Grease, established the Olivia Newton-John Foundation Fund, an independent charity sponsoring global research into plant medicine for cancer.

The charity says it is “committed to realising a world beyond cancer”, through pioneering scientific research into less invasive ways to treat the disease, and her family asked well-wishers to support it in her memory.

She also founded the Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia, a public hospital dedicated to innovative treatments and wellness programmes to support patients’ mental health.

The cancer facility is also a hub of research, with more than 200 clinical trials in progress focused on immunotherapies – which helps the body’s immune system to recognise and fight cancer cells – and personalised medicine diagnostics.

When asked in a September 2018 interview with Australia’s Channel 7 if she was scared following her third cancer diagnosis, Dame Olivia said “I believe I will win over it” and vowed “that’s my goal”.

But in a typically candid admission, she added: “I’d be lying if I said I never go there. There are moments; I’m human. If I allowed myself to go there, I could easily create that big fear. But my husband’s always there, and he’s there to support me.”

Dame Olivia, who underwent a partial mastectomy after her 1992 diagnosis, revealed in 2018 that she was using a holistic health regimen which included cannabis/cannabidiol, also known as medical marijuana.

She explained her husband grew marijuana for her and made tinctures for her to consume along with plant medicine, as she did not like taking prescription medicine and found it helped with anxiety, sleep and pain.

The same year, she had to learn to walk again when the disease spread and she fractured the base of her spine.

Only last year, by which time her cancer was at stage four, she appeared on The One Show on the BBC alongside her daughter Chloe Rose to say that “every day is a gift”.

“Oh no, I’m fine, I just – listen, I was dealing with metastatic breast cancer for the last seven years but I feel great,” she said. “I feel really wonderful.”

The Hopelessly Devoted To You singer campaigned for kinder ways of tackling cancer, aside from the traditional treatments she underwent of surgery, chemotherapy and radiotherapy.

But it was the positive outlook of Dame Olivia, who was born in Cambridge and lived most of her life in Australia and the US, that captivated many.

She told the Guardian in 2020 that cancer was “my life’s journey – it gave me purpose and intention and taught me a lot about compassion”.

She rejected two stereotypes widely used about cancer – the first being terminology around “battles”, and the second being “death sentence” predictions by doctors of how long a cancer patient may live.

“I don’t think of myself as sick with cancer,” she told the newspaper in an interview. “I choose not to see it as a fight either because I don’t like war. I don’t like fighting wherever it is – whether it’s outside or an actual war inside my body.

“I choose not to see it that way. I want to get my body healthy and back in balance. Part of that is your mental attitude to it. If you think: ‘Poor me,’ or ‘I’m sick,’ then you’re going to be sick.”