For any parent of very small children, the news your brain cancer had returned after eight years and is terminal would be almost impossible to comprehend.

But that was the grim diagnosis given to Melbourne mother-of-two Sara Chivers in March this year.

She had three tumours, they were inoperable and they were incurable.

"It's just devastation and a lot of grief," Sara told 7.30.

"But also wanting to make the most of the time that we have."

But four weeks ago, Sara's life took another extraordinary and heartbreaking twist.

Sara and her husband, Leigh, discovered their 18-month-old son, Alfie, also had brain cancer — a completely different type, but also malignant, aggressive and terminal.

"He hasn't even started his life yet," Sara said.

"He hasn't been able to do all of the things that I've been able to do, you know, in my 34 years to date."

"So it's just horrible, absolutely horrible. And heartbreaking."

"You just don't expect the worst scenario to keep happening over and over again," Leigh said.

"But it has for us. A couple of times."

'Exceptionally, exceptionally rare'

Alfie Chivers when he first went into hospital. ( Supplied: Sara Chivers )

Alfie's tumour is what is known as an atypical teratoid rhabdoid.

According to his neurosurgeon, Chris Xenos, its incidence is one in 3 million.

Sara has what is known as glioma.

Her neurosurgeon, Bhadu Kavar, has never seen another parent and child with these two conditions at the same time.

"I think that's exceptionally, exceptionally, rare," Mr Kavar said, comparing it to a case of lightning striking twice.

Brain cancer kills more children than any other disease.

Despite the mortality rates for all other rates of cancer improving by 20 per cent over the past 30 years, brain cancer mortality rates have only improved by 1 per cent.

The Federal Government announced this week it would match $50 million in funding from the Cure Brain Cancer Foundation and Twiggy Forrest's Minderoo Foundation to fund brain cancer research.

But the Cure Brain Cancer Foundation still needs to raise $20 million of that money through fundraising, so Sara desperately wants to draw attention to the need for research.

"It just provides hope to families like mine that have been devastated by the impacts of brain cancer," a tearful Sara told 7.30.

"Probably not in my lifetime, but definitely in Alfie's lifetime, I'm hoping that they'll find a cure."

An operation to buy some time

Surgeons had just operated on Sara Chivers' tumours when she heard that Alfie also had brain cancer. ( Supplied: Sara Chivers )

Mr Kavar said brain cancer was "a common, devastating tumour".

"We need to understand it better," he said.

"And the only way we can understand it better is by working harder at its research."

Sara seemed healthy and was training for a half marathon in 2008 when she had a seizure and was diagnosed.

She had surgery and remained cancer-free until March this year, when a scan showed three aggressive new growths in her brain.

"My neurosurgeon said that we couldn't operate because of the position of the growths," she said.

"It really gave us an opportunity to assess our priorities and really put a value on the things that are most important and also celebrate those special milestones."

A month ago, a further scan showed two of Sara's tumours had shrunk from treatments she'd been receiving, but the third had grown exponentially.

This paralysed Sara's right arm and leg. But it also made surgery possible.

In late October, she had an operation to shrink the large tumour in the hope it would give her more mobility and more time.

'This wasn't even on the scale of my worst fears'

Leigh and Sara Chivers with their sons Hughie (l) and Alfie (r). ( Supplied: Sara Chivers )

At the same time, Alfie developed symptoms, which at first were put down to teething or an infection.

But after he was rushed to emergency and high-grade antibiotics did nothing, Leigh noticed a disturbing development in the middle of the night — Alfie, too, was losing mobility on one side.

"He was awake during what I now know was seizures," Leigh said.

"And he was just crying like a baby, but had a little shake in his left arm."

A scan revealed the unthinkable news: Alfie had a tumour the size of a pear in his brain.

Leigh called Sara who was with her mother.

"I just said that they found a mass on Alfie's brain," he said.

"I just heard screaming."

"We just all started crying together," Sara said.

"It just haunts me because I knew that that was the start of our lives never going to be the same again. This wasn't even on the scale of my worst fears.

"To think that he has to go through this journey, at 18 months old.

"It's been so, so hard to see him go through that."

'I won't let him be a statistic'

Sara Chivers wants more time to help Alfie beat his cancer. ( Supplied: Sara Chivers )

Alfie has since had three operations to remove as much of the tumour as possible and to reduce the fluid in his brain.

Sara's operation on October 25 was high-risk but went successfully.

She's currently in rehab, and has some increased mobility.

She's hoping it buys her more time to help Alfie with his fight.

"Because the mortality rates for children aren't great," Sara said.

"And I won't let him be a statistic."