American singer-songwriter Janet Jackson is reportedly undergoing tests for throat cancer.
"Doctors found a growth on Janet's vocal cords that could be serious," a source told Radar Online.
"It's a medical condition that has to be taken care of immediately."
The sister of the late Michael Jackson announced on Christmas Eve that she was forced to postpone her Unbreakable World Tour, which was due to begin in January.
"I need you to know, I learned today, from my doctors that I must have surgery soon," Jackson told her fans.
"It breaks my heart to tell you that I am forced to postpone the Unbreakable Tour until the spring... Please pray for me, my family and our entire company during this difficult time."
Australian dancers recently created a video tribute to Janet Jackson by performing to her new track Burn It Up around Sydney.
"Hey you guys, I love how you are Burning it up in Australia! xoxo #BurnItUp #Unbreakable," Jackson tweeted, sharing the video.