Eva Pierce was struck down with a grade three anaplastic ependymoma days before her second birthday. Surgeons spent nine hours removing the tumour "bigger than a golf ball" from her brain, after which she was able to walk and talk for the first time.
However, the treatment she needs to beat the disease and give her a near-90% chance of survival, is not yet available in the UK.
Her parents, Claire and Kenny, are waiting to hear if the NHS will pay the £250,000 needed for Eva to travel to America for specialist proton beam therapy.
The child-friendly cancer treatment lets doctors target a radioactive beam at cancer cells without harming surrounding healthy tissue.
Mr Pierce, 31, from Kirkmuirhill, said: "It's her only hope. She is getting chemotherapy just now but there is a 50/50 chance of the tumour returning. Because it is a very aggressive cancer, it is likely to come back. With the proton therapy there is an 87% chance of it not coming back. "
The couple have been told by doctors Eva meets "all the criteria" for the NHS to cover the cost of the treatment for her and her parents to travel to Florida University, Jacksonville, or the Pro-cure Centre in Oklahoma.
Their bid comes a day after the Scottish Government agreed to fund 90% of the £300,000 needed to treat Mackenzie Furniss, 9, of Sauchie, Clackmannanshire, who has stage four neuroblastoma.