The Irish Cancer Society has said cancer patients are struggling to cover the living costs associated with their disease.
Applications to the charity's Financial Aid Scheme have increased by 36% in the last three years.
The society now provides over €1m annually to cancer patients who need financial help, which represents roughly 5% of its total annual spend.
The vast majority of its money goes into research funding.
Speaking on RTÉ's Morning Ireland, Kathleen O'Meara of the Irish Cancer Society said 1,700 people applied for the scheme this year because they were struggling to cope financially.
She said that for many people in the past this scheme was a "last resort", but more and more people were finding it difficult to meet costs, including transport and heating.
The society has also expressed concern that patients in treatment and who are waiting for medical cards are being asked to pay for chemotherapy treatment.
It said that some have received letters from debt collection agencies for payment for hospital charges and chemotherapy treatment.
It says this could have extra psychosocial effects on patients.
Many public patients must pay the statutory inpatient treatment charge of €75 a night, subject to a maximum of €750 a year.
The outpatient charge is €100, but patients on return visits for the same illness face no extra charge.
Ms O'Meara said she was concerned that the €75 charge would discourage people from receiving chemotherapy treatment.
The HSE says that patient charges are a statutory charge, set down by law, which have been in place for some time.
It says there is no new charge for cancer patients.
The executive said it has a statutory obligation to impose the charges and to recover the monies owed to hospitals.
Every charge not collected represents less money to spend on other areas of care.
The HSE said that cancer patients are entitled to apply for discretionary medical cards in certain circumstances.