Cancer patients and oncologists are calling for more cancer drugs to be subsidised on the PBS amid fears thousands of people are missing out on treatments because they can't afford them.

The National Oncology Alliance has surveyed oncologists and found that 3500 cancer patients are forking out $60,000 a year for potentially lifesaving medication, while another 6000 miss out because they don't have the money.

The lobby group wants Pharmaceutical Benefits Advisory Committee (PBAC) to end the practice of just subsidising cancer drugs for specific forms of the disease so people with different types of cancers can access cheaper treatments.

The independent advisory group is due to meet on Friday to consider its next recommendations for which medicines should be listed on the PBS.

NOA is concerned that while there are many innovative oncology medicines that have potential across multiple cancer types, not all patients, particularly those with rare forms of the disease, are given subsidised access to them.

"We will work with the PBAC, and all sides of politics, to ensure the reimbursement of medicines in this country adapts to allow subsidised access to exciting treatment options for patients, regardless of cancer type, as the days of a one size fits all approach are behind us," NOA co-chair Richard Vines said in a statement on Tuesday.

While about 30 per cent of cancer diagnoses involve rare forms of the disease, about half of all cancer deaths involve less common cancers.

NOA argues that this situation has barely changed in the past two decades, in part due to the limitations around reimbursement for treatments for rare cancers.

Higher prices and resource intensiveness for both industry and government are factors contributing to this slower reimbursement, it said.

NOA is calling on the PBAC to allow managed access to subsidised cancer treatments for people with rare forms of the disease.

"A provisional PBS listing through managed access could be a solution in situations where there is a high level of uncertainty in a PBAC submission for a rare cancer indication, with additional real-world evidence collection helping to build the case for eventual PBS listing," NOA said.