"There are no doctors that will confirm that," Crow, 50, acknowledged on "Katie." "[But] I do have the theory that it's possible that it's related to that. When I was promoting my first record, I did hours of [interviews] on the old archaic cell phones."
Sheryl says the tumor is in the spot where she would hold her phone, and explains that she initially suspected it was early-onset Alzheimer's because she felt "mushy" -- forgetting lyrics and spacing out onstage.
Crow, who successfully battled breast cancer several years ago, tells Couric the pinky-sized tumor is "nothing I have to worry about," but she will continue to keep a close eye on it.
RELATED ON WONDERWALL:
- Feb. 04, 2016 There's a very good reason why Rihanna is single
- Feb. 01, 2016 See the stars who've debuted new hair styles in 2016