Hannah Day, of Victoria, B.C., who was thought to have overcome both stomach cancer and leukemia during her short life, has relapsed and will die at home, says her devastated mother.

"It just all came crashing down, it's like, 'This is real, like, this is really happening,'" said Hannah's mother Brooke Ervin tearfully, speaking via Skype on her way to take Hannah for tests at BC Children's Hospital.

"We'll go over [to Vancouver], I'll shake the doctor's hand, I'll say, 'Thank you for everything that you did,'...then I'm going to take her home. I want her to die at home.

"She's spent more of her life in hospital than at home. I don't want to put her back on those machines. I don't want to give her more drugs that will make her sick. I want her to be at home."

'Her fight is over'

Hannah was first diagnosed with a rare form of cancer at the age of three, when a malignant tumour was found in her stomach. (CBC)

Hannah was showing zero signs of leukemia after Ervin donated one litre of her stem cells to her daughter in a last-ditch stem cell transplant.

But on Tuesday, says Ervin, Hannah fell ill while playing outside. In hospital, she went rapidly downhill, she said, and doctors told them Hannah had relapsed.

"It could be a week, it could be a month, it could be six months, we have no idea. All we know is that it's going to happen fast and this is it. Her fight is over. She has lost her fight."

Long battle with cancer

Hannah was first diagnosed with a rare form of cancer at the age of three when a malignant tumour was found in her stomach. She underwent intensive treatment and went into remission.

The drug that cured her, however, is thought to have caused her subsequent leukemia.

Day's family searched for a stem cell donor match while the little girl underwent chemotherapy. However, that treatment did not go well and her leukemia returned with a vengeance. The stem cell treatment was her last resort.

"She's never had it easy," said Ervin. "Now all I can hope for is that she isn't going to suffer."