Taylor Swift reveals her mom was diagnosed with a brain tumor

FILE - In a Monday, Dec. 16, 2019 file photo, Taylor Swift attends the world premiere of "Cats," at Alice Tully Hall, in New York. (Photo by Evan Agostini/Invision/AP, File)

Music superstar Taylor Swift is opening up publicly about the health struggles her mom has faced recently.

In an emotional interview with "Variety" ahead of her upcoming documentary, Swift revealed for the first time that while her mother, Andrea, was undergoing chemotherapy for cancer treatment, doctors made another discovery.

“While she was going through treatment, they found a brain tumor," Taylor told "Variety." "And the symptoms of what a person goes through when they have a brain tumor is nothing like what we’ve ever been through with her cancer before. So it’s just been a really hard time for us as a family.”

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Her mother's health is one of the reasons why Swift decided to limit the touring schedule for her latest album, "Lover."

The Netflix-produced documentary "Taylor Swift: Miss Americana" was filmed when her mother's cancer had returned for a second time.

According to "Variety," the documentary shows in a light-hearted scene that one way her mom decided to push back against cancer was to bring a dog, which she lovably named her "cancer dog," into their feline-friendly family.

"Variety" interviewed Swift earlier this month, just a few hours before the Golden Globes. A song she co-wrote with Andrew Lloyd Webber for "Cats" was nominated for Best Original Song, but didn't win. "Cats" has been widely panned by critics and is a box office flop. But Swift told "Variety" that she still had a great time working on the movie.

“I’m not gonna retroactively decide that it wasn’t the best experience. I never would have met Andrew Lloyd Webber or gotten to see how he works, and now he’s my buddy. I got to work with the sickest dancers and performers. No complaints,” Swift explained.

"Taylor Swift: Miss Americana" premieres on Jan. 23 during the opening night of the Sundance Film Festival, then debuts in theaters and on Netflix on Jan. 31.