Newton-John, a four-time Grammy winner, had disclosed several years ago that breast cancer had metastasized and spread to her back, forcing her to cancel performances.
Source: Hindu
Twenty-five years earlier Newton-John had undergone a partial mastectomy and gone on to establish a cancer treatment-research facility in Australia.
Newton-John also beat out country stars Loretta Lynn and Dolly Parton to win the Country Music Association's female singer of the year award in 1974.
Newton-John, whose sister died of brain cancer, became an advocate after her first bout with breast cancer and she established the Olivia Newton-John Cancer Wellness and Research Centre in her hometown of Melbourne.
Newton-John, whose grandfather was German-born Nobel laureate Max Born, a physicist, finished fourth in the 1974 Eurovision singing competition while representing the United Kingdom.