Olivia Newton-John, one of the recording industry’s top-selling artists of all time, has been told that her breast cancer has returned and has metastasized to her lower back, according to media reports. The Los Angeles Times reports that the 68-year-old singer said she has “reluctantly” postponed her June concert dates.

Newton-John, known for a string of ’70s hits including “Please Mr. Please,” “Have You Never Been Mellow” and “I Honestly Love You,” posted a message on social media saying: “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 notes that those therapies include a short course of photon radiation therapy in addition to “natural wellness therapies.”

Newton-John was first diagnosed with breast cancer in 1992. The Times notes that at that time “she underwent chemotherapy after a modified radical mastectomy with reconstruction. Her treatment also included acupuncture, which she said helped her with nausea, as well as yoga, meditation and massage.”

Newton-John has reportedly sold about 100 million records worldwide.