05/30/2017 04:50 EDT | Updated 05/30/2017 04:54 EDT

Olivia Newton-John Reveals Her Breast Cancer Is Back; Cancels Tour

NEW YORK — Olivia Newton-John says she has breast cancer and is cancelling her June tour.

The 68-year-old singer said Tuesday she initially thought she was suffering from back pain, but learned it was "breast cancer that has metastasized to the sacrum.''

Newton-John said she will complete "a short course of photon radiation therapy'' and hopes to perform later this year. She said she will be treated by the medical team at the Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia.

Says Newton-John: "I decided on my direction of therapies after consultation with my doctors and natural therapists.''

Ticket buyers will be refunded for the cancelled shows. She was scheduled to perform two shows in Niagara Falls, Ont.

"Rescheduled concert dates will be posted at in the coming weeks," read a Facebook post.

This isn't her first fight with the disease. She was diagnosed with breast cancer and recovered in 1992.

With files from Emma Prestwich