Australian-born actress and singer Olivia Newton-John died on August 8 at the age of 73 after a 30-year battle with metastatic breast cancer.
Best known for her role as Sandy in the 1978 film musical "Grease," Newton-John also hit the charts with singles like "Physical" and "Magic."
According to CNN, Newton-John was first diagnosed with breast cancer in 1992, then underwent a partial mastectomy, followed by chemotherapy and breast reconstruction.
The cancer was cured, but in 2013 it returned as a tumor in her shoulder.
The cancer returned in 2017 as a tumor at the base of the singer's spine.
That time between recurrences is unusual for breast cancer, says CU Cancer Center member Nicole Christian, MD, especially low-grade estrogen-positive breast cancer, which tends to be less aggressive.
There can be long periods of healthy remission of the disease, only to see it return to other parts of the body.
"There are types of breast cancer where the window in which the cancer can return to metastatic disease is very long," said Christian, surgical oncology at the UK School of Medicine.
"For many cancers, we think of a five-year window—if you've done it for five years, you're in the clear.
But with breast cancer, the timeline for the cancer to come back can be very long."