Taylor Swift has shared the sad news that her mother, Andrea Finlay, is battling cancer.

In a post on her Tumblr page titled Just so you know…, the singer revealed to her fans that a series of health tests had lead to her mother being diagnosed.

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Swift with her mother Andrea at the 2010 Grammys. Photo: Getty

“For Christmas this year, I asked my mom that one of her gifts to me be her going to the doctor to get screened for any health issues, just to ease some worries of mine,” the singer wrote.

“She agreed, and went in to get checked. There were no red flags and she felt perfectly fine, but she did it just to get me and my brother off her case about it.

“The results came in, and I’m saddened to tell you that my mom has been diagnosed with cancer. I’d like to keep the details of her condition and treatment plans private, but she wanted you to know.”

Swift did not say what type of cancer the 57-year-old was diagnosed with, but emphasised the fact her mother wished to share the news with her millions of fans.

“Thank you for caring about my family so much that she would want me to share this information with you,” the 25-year-old wrote.

“I hope and pray that you never get news like this.”

Swift has one sibling, a younger brother named Austin. Her mother has a close bond with her daughter’s fans, as does her father, Scott.

Swift’s parents live in Nashville in a home their daughter purchased for them in 2011.

#PrayForMamaSwift was a trending hashtag on Twitter on Thursday.