Four-time Grammy Award-winning singer Olivia Newton-John, known for hits including “You’re the One That I Want,” “Have You Never Been Mellow” and “Please Mr. Please,” says she has been diagnosed with cancer for the third time in three decades, the AP reports.

Newton-John, who turns 70 on Sept. 26, reportedly told the Australian news program “Sunday Night” that doctors found a tumor in her lower back in 2017.

“Newton-John says she’s ‘treating it naturally and doing really well,'” the AP reports. “The ‘Grease’ star says for pain, she is taking cannabis oil, made from marijuana her husband grows in California. She has undergone radiation treatments and has cut sugar out of her diet.”

The singer is quoted saying: “I believe I will win over it.” She also said she hopes her native Australia will legalize medical marijuana.

“Newton-John was first diagnosed with breast cancer in 1992, undergoing a partial mastectomy and reconstruction,” the AP reports. “She was diagnosed with breast cancer again in 2013.”