Taylor Swift arrives at the Billboard Music Awards at the MGM Grand Garden Arena, in Las Vegas. Picture: AP
Taylor Swift's mother Andrea is battling cancer for the second time, four years after she previously fought the disease.

The 29-year-old singer first revealed her mother Andrea had been battling the disease four years ago, and in a personal essay written for Elle magazine about the 30 life lessons she's learned so far, she has said the cancer has sadly returned.

She wrote: "I've had to learn how to handle serious illness in my family. Both of my parents have had cancer, and my mom is now fighting her battle with it again."

The 'Gorgeous' hitmaker says her parents' battle with cancer has taught her there are "real problems" in the world, and she no longer worries so much about every minor detail in her life.

She added in the April issue of Elle magazine: "It's taught me that there are real problems and then there's everything else. My mom's cancer is a real problem. I used to be so anxious about daily ups and downs. I give all of my worry, stress, and prayers to real problems now."

Taylor had first opened up about her mother's diagnoses in April of 2015, when she posted the difficult news on her Tumblr account.

Her message read: "I'm writing to you with an update I wish I wasn't giving you, but it's important and I'm used to sharing important events in my life with you. 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.

"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. 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."