(CNN)Pop star Taylor Swift, who has built an intense bond with her fans by sharing personal details of her life, revealed some sobering news Thursday: Her mother has cancer. The singer did not divulge the nature or severity of the cancer, saying "I'd like to keep the details of her condition and treatment plans private." Andrea Swift, 57, who years ago quit her job as a mutual fund marketing executive to raise Swift and Swift's younger brother, Austin, has joined her famous daughter on tour and in several of her videos. In a post on Tumblr, the blogging platform, Swift said that for Christmas last year, she asked her mom to get screened for potential health issues, "just to ease some worries of mine." Her mother felt "perfectly fine" but went to the doctor for tests anyway "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 added. #PrayForMamaSwift was a trending hashtag Thursday on Twitter, where Swift's legions of fans offered prayers and messages of support. Within an hour and a half, Swift's tweet about her mom had been retweeted more than 21,000 times. Many fans shared "there's something in your eyes that says we can beat this," a lyric from Swift's 2008 song "Change." Swift also urged her fans to make sure their parents get screened for cancer and other potential health problems. "She wanted you to know because your parents may be too busy juggling everything they've got going on to go to the doctor, and maybe you reminding them to go get checked for cancer could possibly lead to an early diagnosis and an easier battle ..." she wrote. "Or peace of mind in knowing that they're healthy and there's nothing to worry about." Swift, 25, added that "usually when things happen to me, I process them and then write music about how I feel, and you hear it much later. This is something my family and I thought you should know about now. "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." Andrea Swift and Swift's father, Scott Kingsley Swift, live in Nashville, Tennessee, in a mansion bought by their daughter in 2011 for $2.5 million.
Pop star Taylor Swift revealed Thursday that her mom has cancer . The nature and severity of Andrea Swift's cancer have not been divulged .