Pop superstar Taylor Swift received an outpouring of support on Thursday after announcing that her mother has cancer. 

Fans of the singer began the hashtag #PrayforMamaSwift, which trended for hours on Twitter. 

Swift shared the somber news on her Tumblr account in a post entitled "Just so you know..."

"Usually when things happen to me, I process them and then write music about how I feel, and you hear it much later," she wrote. "This is something my family and I thought you should know about now."

The former country artist said she asked her mother, Andrea, to undergo health screenings around Christmas. Mrs Swift was seemingly healthy, but her daughter wanted her to see a doctor for her own peace of mind. 

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

The 25-year-old urged her fans to remind their busy parents to undergo cancer screenings in the hopes of getting an early diagnosis or confirmation that everything is fine. She also said that her mother wanted to explain why she will not be at as many of her daughter's concerts. 

"She's got an important battle to fight," Swift added. "Thank you for caring about my family so much that she would want me to share this information with you. I hope and pray that you never get news like this."

After word of the diagnosis circulated Swift's nearly 56 million Twitter followers, a wave of tweets praying for her mother and wishing her good health followed. Celebrities including Cara Delevingne, Mindy Kaling, and Sharon Osborne also offered their support.