Australian singer Olivia Newton-John has announced that she was diagnosed with cancer for a third time. The 69-year-old singer is most well known for her role in the hit movie “Grease.” According to Channel24. Doctors found a tumor at the base of Newton-John’s spine. Since the diagnosis she has undergone radiation treatment and used natural therapies, such as using cannabis oil. In the past, Newton-John has been diagnosed with breast cancer and cancer on her shoulder.