The parents of Elyse Johnson have been dealt a crushing blow in their race to save the little girl's life - her brain tumour is growing again and she may have only weeks left to live.

The 3-year-old's tumour, which has left her a virtual quadriplegic, is only 1mm away from pressing on the base of her brain stem.

Doctors say when that happens, nothing more can be done for the preschooler.

Elyse's mother Casey Johnson wanted to thank the public for their incredible generosity in donating more than $60,000 for her treatment.


"It's given us so much more time with her as it is," she said.

"She should have only had a few months but it's been 16 months almost."

Johnson and her husband Jamie, who farm near Taupo and are in the middle of calving, said they also hoped to afford a family holiday with Elyse and her older brother Blake to make the most of the time they have left together.

The family received the devastating news of Elyse's prognosis on Monday after she underwent another brain scan. It showed that although the aggressive tumour - a diffuse intrinsic pontine glioma (DIPG) - remained stable, it had grown 2-3mm each way.

A cyst on her spine is also growing and could eventually cut off Elyse's ability to breathe.

Doctors have given the once feisty toddler up to two months to live, a gut-wrenching outcome for the parents who have been treating Elyse with alternative therapies since she was diagnosed 16 months ago.

Johnson, 25, said the most difficult part to accept was that Elyse shows no signs of deterioration.

"It's a bit of a shock because she's still doing pretty good. She's moving her facial features more. She's still relaxed and really aware."

Though Elyse, who once loved dancing and playing with Blake, cannot walk and talk, Johnson said her daughter had defied an initial prognosis of 12 months to live.

Elyse Johnson's brain tumour is growing but she is still aware her parents say. Photo / Supplied
Elyse Johnson's brain tumour is growing but she is still aware her parents say. Photo / Supplied

"The doctor can't say it's [the alternative therapies] working, but he said he thinks it has done something."

The family are continuing to fundraise for Elyse's $4000 a month alternative treatments including the medical marijuana spray Sativex.

Johnson said the mouth spray made with cannabis extract, which Elyse began having eight months ago, appeared to have improved her mobility.

A Givealittle page set up by friends of the Johnsons has raised more than $60,000 but that purse is down to $15,000 after paying for all the treatments.

"And if she does go downhill then she's going to be on more [cannabis] oil for pain relief as well."

Despite the grim reality, friend and fundraising organiser Victoria Beacock said the family and their supporters hadn't given up hope completely.

The Johnsons were hoping to take Elyse to a clinic in Mexico for an unproven chemotherapy treatment.

"She [Elyse] has been a strong little princess to fight for this long beating all odds given by the doctors," Beacock said.

"We definitely believe the medicinal cannabis has contributed to her surviving this long and are adamant that if the Sativex had been offered upon diagnosis [not 7 months later] then she would have had a much better chance of beating this awful cancer."