Almost two-thirds of women with advanced breast cancer experience financial difficulty as a result of their diagnosis, with average out-of-pocket costs of $687 each month.
A Breast Cancer Network Australia survey of 580 women found financial difficulties affected women in the private and public healthcare systems, and drugs not included on Australia's list of subsidised medicines caused the greatest burden.
Women reported average monthly out-of-pocket costs of $687 associated with their treatment, including costs of $817 in the private hospital system and $531 in the public system.
The biggest cost was for medicines not included on the Pharmaceutical Benefits Scheme. Women reported spending an average of $5277 on non-subsidised drugs over the course of their illness.
They also reported significant outlays for surgical costs and radiotherapy, largely in the private system.
Of the women surveyed, 60 per cent said the disease had caused them financial difficulty in the past week. A quarter said the difficulty was "quite a bit" or "very much".
One of the women who took part in the survey was Sharon Driessen, 48, who was diagnosed with secondary breast cancer in November 2012.
Mrs Driessen was first treated for breast cancer 10 years ago and remained healthy for eight years until scans revealed the cancer had returned and spread to her liver.
She has mostly received treatment in the private system and said out-of-pocket fees, including for specialists, surgery and medicines, had cost her about $15,000 since being diagnosed with secondary cancer.
"No scheduled fee is ever a scheduled fee, it's always more than that and private health insurance never covers it, nor does Medicare," she said.
Breast Cancer Network Australia chief executive Maxine Morand said it was concerning that women with secondary breast cancer had to face significant financial difficulties in addition to the physical and emotional impact of treatment.
It was frustrating that delays for cancer drugs to be listed on the PBS were leaving patients having to fund their own treatments or go without, she said.
"These drugs can considerably improve quality of life. Families are burdened with paying for expensive new drugs on top of all the other costs of treatment."
Ms Morand said many people would be surprised at the costs associated with cancer treatment, which usually came on top of a reduction in income.
"There really are very significant out-of-pocket costs associated with treatment, particularly in the private system, and I think people really need to go into it with their eyes wide open," she said.
About 15,000 Australian women are diagnosed with breast cancer each year and 2700 die of the disease. It is estimated 9000 Australian women are living with secondary breast cancer.
