Luft, whose parents were Garland and producer Sid Luft, was rushed to the hospital by her husband Colin Freeman, after she collapsed backstage on Friday, following her second sold out show at London’s Pizza Express Jazz Club, the singer’s rep Victoria Varela confirmed to PEOPLE.
Varela also told PEOPLE that Luft’s husband Freeman had expressed concern that the singer, 65, was forgetting lyrics and parts of her monologue.
According to Varela, after Luft was admitted to the hospital, she was initially diagnosed with a brain tumor. The singer is currently in remission from breast cancer, which she battled for over six years.
Luft’s rep told PEOPLE more information will be available after she undergoes additional medical tests and examinations.
Most recently Luft — who received an Emmy for producing Life with Judy Garland: Me and My Shadows, which was adapted from her 1998 memoir — starred in a production of Irving Berlin’s Holiday Inn at Seattle’s Fifth Avenue Theatre. The singer’s half-sister is actress Liza Minnelli.