Sheryl Crow thinks her benign brain tumour was caused by her mobile phone.

The 50-year-old singer - who has previously battled breast cancer - claims no one will confirm usage of the device was what caused the tumour, but she feels like it might be behind it.

She said: ''There are no doctors that will confirm that. But I do have a theory that it's possible that it's related to that. I used to spend hours on the archaic old cell phones.''

Initially, Sheryl was concerned she had Alzheimer's disease when she began forgetting song lyrics, but is glad the lump is not of serious worry.

Speaking on 'Katie' she said: ''I was worried I had early onset Alzheimer's. It's nothing to worry about. But it was definitely a sobering moment.''

The 'Soak Up The Sun' singer previously revealed it was memory loss which led her to get the problem checked out.

She said: ''I worried about my memory so much that I went and got an MRI. And I found out I have a brain tumour.

''And I was, like, 'See? I knew there was something wrong.' I haven't really talked about it...But it's benign, so I don't have to worry about it. But it gives me a fit.''