Mental health and emotional support has been forgotten when childhood cancer is treated, a charity has found in a survey of parents and carers.

When her two-year-old son Jamie was diagnosed with cancer, Nicky Sherlock was forced to leave her family and move from the country to the city.

"He was a very healthy little farm boy who never got sick, but he started complaining of a sore tummy, wasn't eating and just felt pretty miserable," Mrs Sherlock told AAP.

After initially being told he had bowel issues and tonsillitis, Jamie was diagnosed with leukaemia in September 2019, and the treatment and surgeries began right away at Perth Children's Hospital.

"From there it's just a whirlwind of torturous things happening to your child," she said.

"I had to leave my daughter behind with my mum and dad, because I was in hospital for long periods of time and she was going into high school. My husband had to stay to work. It was a very big disruption in all of our lives."

To stay by her toddler's side, Mrs Sherlock moved from the regional town of Boddington to Perth, two hours away.

She stayed in Perth for a year and says the cancer treatment and time apart had "massively" impacted the whole family mentally and emotionally.

After being away from her mum, Mrs Sherlock's daughter Jess developed severe anxiety, including panic attacks.

Sometimes she can feel jealous of her brother being prioritised over her.

"It has damaged our relationship so much," Mrs Sherlock said.

"It's very hard to explain to her that he actually needs me more at the moment than what she does. To say that to any of your children is awful."

Mrs Sherlock suffers from post-traumatic stress disorder and is constantly in "fight or flight" mode.

Despite this, no mental health support was offered to the family following Jamie's cancer diagnosis.

"You're pretty much just left on your own," she said.

Mrs Sherlock is one of about 10,000 Australian parents, children and siblings missing out on vital support after a child cancer diagnosis, charity Redkite has found.

"In Australia, we have the best medical care for kids with cancer and that's where the focus is, on medical survival," Redkite chief executive Monique Keighery told AAP.

"What that means is that other serious impacts from childhood cancer take second place and in many cases they're hidden. There's major gaps and we need to be doing more."

The charity released its Hidden Health Crisis report on Wednesday, based on a survey of 700 parents and carers of children with cancer, which found two thirds of families are not given the emotional and mental support they need.

People living in remote or regional areas are disproportionately affected, with the biggest gaps in support found to be after a child's cancer treatment has ended or during bereavement.

Some parents feel isolated due to a lack of connection with other families experiencing childhood cancer, and about 2500 siblings of children with cancer are not given the help they need.

"There's a lot of things people don't think about when a child is diagnosed with cancer - the family separations happen immediately, family income is reduced almost overnight - in addition to having a really sick child," Ms Keighery said.

The pandemic has brought unprecedented levels of demand for Redkite's services and the charity is calling for more government funding.

"Childhood cancer is a complex trauma and it needs specialised support, with experts in the paediatric oncology space. We're well positioned to provide that support," Ms Keighery said.

"We provide a number of programs that need to be expanded and extended, particularly in helping families transition home post-treatment.

"For every family we're helping, there's more we're not able to at the moment."

Two years on, the Sherlock family is living together again in Boddington, with Mrs Sherlock and 14-year-old Jess both seeing psychologists.

Jamie is now four and has another year left of treatment, while Jess is thriving in a home-school environment.

With the help of Redkite, the family has been offered counselling and financial support.

Lifeline 13 11 14

beyondblue 1300 22 4636

Kids Helpline 1800 55 1800 (for people aged 5 to 25)