Taylor Swift considered cancelling her world tour when her mother was diagnosed with cancer.

The 'Bad Blood' hitmaker - whose '1989' concert series kicked off in Tokyo on May 5 - was left devastated when Andrea Finlay discovered she had the disease and reportedly contemplated shelving the dates to be by her parent's side.

A source said: ''When her mom got sick, she expressed that she was seriously considering not doing her tour.

''Since the very beginning her mom has travelled with her and been to every concert. Taylor didn't want to do it alone and be worried about her mom and so far away.''

However, Andrea encouraged the 25-year-old pop star to go ahead with the tour and urged Taylor to take more control of decision making as she had previously been involved in everything from costume approval to merchandise to marketing on behalf of her daughter.

The source added to the New York Daily News newspaper's Confidenti@l column: ''She makes every decision herself, early on it was her mother.''

The 'Blank Space' singer announced the sad news of her mother's illness in Instagram, explaining how she had urged Andrea to undergo medical tests last December.

She told her fans: ''The results came in and I'm saddened to tell you that my mom has been diagnosed with cancer.''

Despite her mother's illness, Taylor has still been joined on some of her tour dates by Andrea and other members of her family, as well as boyfriend Calvin Harris.