When Ebony Gaylor was diagnosed with bowel cancer at 38 years old, she couldn't believe it was happening to her.

The fit, young executive-level Melburnian thought issues in her gut were most likely too much gluten or irritable bowel, so she put off getting tested.

"I'd try all the usual things like increasing exercise or less coffee, or getting rid of bread or whatever – it just wasn't working," she told AAP.

"I had not planned on getting cancer. It's not even that it was an old person's disease – I didn't think it was a 'me' disease."

When the "you've got cancer" blow finally landed, the young mum couldn't just put the rest of her life on hold to undergo treatment.

And treatment was brutal. Chemotherapy, radiation, colostomy bags, having part of her bowel, lymph nodes and rectum cut out.

"It's not just can you turn up for chemo and radiation? It affects every aspect of life," Ms Gaylor said.

"Fertility, finances, your relationships, how much you can engage with your child – it just casts such a long shadow."

Ms Gaylor is among a rapidly growing number of under-50-year-olds being diagnosed with bowel cancer, with Australia seeing some of the highest early-onset rates of the disease globally.

In the past two decades, rates have more than doubled among people aged 20 to 29 and tripled among those aged 30 to 39.

Experts are stumped by what's causing the rise, considering everything from microplastics to stress.

Bowel cancer expert Julia Freckelton said it was unlikely there was a single cause.

"We still don't fully understand why bowel cancer is rising so rapidly in younger Australians," she told AAP.

Current evidence suggested the rise could be driven by a combination of lifestyle, environmental and genetic factors including diet, obesity, sedentary behaviour and changes in gut health, Dr Freckelton said.

What is clear is current treatment regimes aren't designed for young people who often have to balance getting better with work, children and other responsibilities.

Ms Gaylor said she felt like a square peg in a round hole undergoing treatment.

"Having a young family, I'm trying to fit in appointments around work meetings, school drop off and pick up and other family kind of stuff," she said.

Dr Freckelton will head a trial program, dubbed ORBIT, to test more flexible support options for young people including telehealth, after-hours appointments, fertility preservation, mental health care and long-term survivorship planning.

Ms Gaylor said younger cancer survivors like her faced decades living with the physical and emotional impacts of their treatment.

"With traditional treatment, you're deciding if you're OK to be infertile, you're deciding if you're OK to have significant portions of your insides removed, you're deciding if you're OK to not have good bowel function for the rest of your life," she said.

"How full-on the treatment is and what it leaves you with afterwards is not built for a 38-year-old woman."

A significant funding boost is needed to support research into the shifting demographics of sufferers and more age-appropriate models of care.

Ms Gaylor has been cancer-free for several years and moved outside of Melbourne for a slower-paced and lower-stress lifestyle.

"Cancer really sucks and nobody should get it –but I don't think it's hopeless," she said.

"We have so many brilliant clinicians and researchers, particularly here in Australia.

"We just need to resource them to do the research and the clinical trials that are needed."