Since being diagnosed with breast cancer two years ago, Kathy Hayes has racked up more than $18,000 in out-of-pocket costs.
Her initial surgery alone made up about $8000.
Ms Hayes shared her story as the Consumer Health Forum launched a new report, Out of Pocket Pain, detailing the experiences of 1200 people and their medical expenses.
The survey found more than a quarter of those treated for breast cancer faced out-of-pocket costs of more than $10,000.
More than a third with chronic conditions like multiple sclerosis faced the same, while one in three believed the cost they would have to cover themselves was not explained before treatment.
For Ms Hayes, she was given a statement on what her initial surgery would cost.
"But we were somewhat surprised with the gap that we had to pay as opposed to the private health insurance," she told reporters in Canberra on Thursday.
While her medical bills have been costly, she has also faced incidental expenses such as wigs, a gym membership to help with side effects and a new wardrobe after she lost a lot of weight.
"You do feel guilty that we've used up our savings for my treatment," she said.
Forum chief executive Leanne Wells said some people had to borrow from family or dip into their superannuation.
"What we found is that, in a nutshell, being sick in Australia these days is a very expensive business," she said.
The forum is backing Labor's call for a Productivity Commission inquiry into the private health insurance system.
They also want:
* Health professionals to make their fees publicly available on an independent website.
* A new system of unnamed referrals so patients can choose their own provider.
Consumer group Choice said costs nowadays could vary between states, surgeons and hospitals, and patients are often angry to be paying high private health insurance premiums only to find insurers aren't stepping in to provide assistance when it's needed.
"It's almost impossible as a consumer to understand what the costs are going to be when you're being recommended for treatment," chief executive Alan Kirkland said.
"We're not going to fix this system through band-aid solutions. We've got to pull the system apart and work out how we put people at the centre of it."
Ms Wells said the current debate over the private health insurance rebate was only looking at one piece of the puzzle and showed why a broad Productivity Commission inquiry was warranted.
"Otherwise the risk is there's policy decisions on the run," she said.