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Did too much time on a cell phone cause Sheryl Crow's benign brain tumor? In a sit-down on Katie Couric's new talk show, the singer says she suspects that's what might have caused her condition.

"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.


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