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.