Cancer patients are paying out up to €1,200 a month on costs linked to their diagnosis.
The Irish Cancer Society is calling on the Government to reduce the financial burden on patients and their families.
It says paying for things like chemotherapy appointments, anti-nausea medication and hospital parking charges means patients are finding themselves "under siege" financially.
Marie Moran, a breast cancer survivor from Co Mayo, faced inpatient charges while dealing with a cancer diagnosis during pregnancy.
She says: "It was such a whirlwind. I was diagnosed with breast cancer 32 weeks into my pregnancy.
"It was such a stressful time for me, physically and emotionally, and to be landed with bills of €80 for each treatment session was a real shock.
"When bills quickly turned into final notices demanding payments, it caused me so much stress and worry at an already difficult time."
In Budget 2020, the Irish Cancer Society is calling for the removal of inpatient charges, a reduction in the Drugs Payment Scheme threshold and the removal of the prescription charge for medical card holders.
The society's chief executive Averil Power says there is public support for such measures.
"In a survey recently carried out by Core Research, almost three in four people supported the removal of inpatient charges while six in 10 said the drug payment scheme threshold should be reduced.
"It also found those on medical cards often don't take all their medication because they can't afford prescription charges.
"More than one in two chose to pay for their child's medication ahead of their own.
"Unable to afford essential medicines, such as anti-nausea tablets, patients' suffer far worse side effects from their cancer treatment than they should.
"This is incredibly unfair and must be addressed".
Read the Irish Cancer Society's full pre-budget submission here