Frankie-Rose Lea is just seven years old, but she only has weeks to live after being diagnosed with a brain tumour.
Experts have told her parents, Michelle and Sam, the only thing that can save her is travelling to America for proton beam therapy.
But they need an extra £110,000 to pay for the life-saving treatment.
The desperate couple have set up a fundraising page, which has already raised £50,000 in just three days, but they need to find the rest of the money fast as their daughter might not make it until Christmas.
They have even put their three-bedroom home in Erith, south east London, on the market and are prepared to be homeless if it saves Frankie-Rose.
Dinner lady Mrs Lea, 36, said: "We are desperate. Right now all we can think about is getting Frankie to America for the treatment she needs to survive.
"We will live in a box if we need to as long as we are together.
"We have worked hard, our house is all we have but we will sell it to save her.
"Some people might criticise us for making the family homeless when we have two other children but I would rather do that than have to tell her brothers we let Frankie die.
"What choice do we have ? If we wait for NHS funding it will probably be too late."
Since Frankie-Rose started chemotherapy in August, her tumour has tripled in size and spread to her spine.
She needs the same treatment as five-year-old Ashya King, but applying on the NHS could take up to eight weeks.
Her tumour is growing so fast, doctors do not expect her to live to see Christmas Day.
Mr and Mrs Lea, who have two others sons, Alfie, 11, and Freddie, five, have put their house on the market for £50,000 under the £220,000 asking price to get a quick sale.
"It would be nice to have a home to come back to after America, but nothing is more important than saving Frankie," Mrs Lea said.
To help Frankie-Rose click here