Actress Olivia Newton-John announced on Monday that she will be cancelling her upcoming tour dates in light of the news her older sister Rona has developed brain cancer.

In a statement Newton-John said, "I received the very sad news that my beautiful sister, Rona Newton-John, has been diagnosed with brain cancer. In light of this news, I have decided to postpone my forthcoming Las Vegas residency to spend time with her and our family."

Newton-John had recently announced plans for a Las Vegas residency with the Flamingo hotel that she says will be postponed until a later date.

The Grammy-Award winning singer sat down with Entertainment Tonight to discuss the saddening ordeal which Newton-John is no stranger to after surviving her own bout with cancer 20 years ago. Newton-John was cleared of breast cancer after undergoing chemotherapy treatments and a mastectomy

"As a cancer 'thriver' myself, as many people are, I am very aware of the importance of love, support and family during this journey she is about to begin," said Newton-John , 64. "I want to thank everyone in advance for respecting our privacy during this difficult time."

Details about Rona Newton-John's cancer, including the type of brain cancer and the severity, have not yet been revealed.

Cancer of the brain is caused by abnormal cell growth around the brain that may result in tumor development. Tumors can either be benign (meaning noncancerous) or malignant (cancerous), in which case they can spread quickly and cause extensive damage to healthy cell growth.

Although benign tumors are considered less severe they may also be accompanied with symptoms such as nausea, headaches, drowsiness and some cases even seizures.