Taylor Swift's mother diagnosed with brain tumour while undergoing breast cancer treatment

Honoree Taylor Swift (L) accepts the Milestone Award from Andrea Swift onstage during the 50th Academy Of Country Music Awards at AT&T Stadium on April 19, 2015 in Arlington, Texas. (Photo by Cooper Neill/Getty Images for dcp)

Taylor Swift has revealed that her mother Andrea Swift has been diagnosed with a brain tumour with the discovery being made by doctors as she underwent chemotherapy for breast cancer.

The 30-year-old shared the symptoms of the tumour were very different what her mother had experienced with her breast cancer.

"While she was going through treatment, they found a brain tumour," Taylor told Variety. "And the symptoms of what a person goes through when they have a brain tumour is nothing like what we've ever been through with her cancer before.

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"So it's just been a really hard time for us as a family."

Andrea Swift and Taylor Swift in the audience at the 2010 American Music Awards held at Nokia Theatre L.A. Live on November 21, 2010 in Los Angeles, California. (Photo by Mazur AMA 2010/WireImage)

The news comes after Swift made the decision to limit her upcoming tour for her latest album, Lover.

She's opted to do just four dates in the United States after embarking on the European festival circuit in the summer, including headlining Glastonbury.

Explaining her personal reasons for the limited tour, Swift shared: “I mean, we don’t know what is going to happen. We don’t know what treatment we’re going to choose. It just was the decision to make at the time, for right now, for what’s going on.”

Swift first told fans about her mother's cancer diagnosis in 2015, although initially kept the details of her illness private.

The ‘You Belong With Me’ hitmaker is the focus of upcoming Netflix-produced documentary Taylor Swift: Miss Americana which explores her life and career.

It will debut the Sundance Film Festival on 23 January before being dropped on the streaming platform on 31 January.