More clarity around the reasons cancer medicines are rejected by the Pharmaceutical Benefits Advisory Committee (PBAC) would better inform discussions between clinicians and their patients, a medical oncologist says.

Dr Deme Karikios, who practices at the Nepean Hospital and is a PhD candidate with the University of Sydney’s NHMRC Clinical Trials Centre, said inadequate cost-effectiveness and uncertainty about the clinical and economic evidence for anti-cancer drugs were the most frequent reasons for rejection.

In a review of all 213 cancer medicine submissions to the PBAC between 2005 and 2014, Dr Karikios found an overall rejection rate of about 56%. The submissions covered 110 unique indications for 60 cancer medicines.

Most drugs (69%) were rejected at least once however 83% were eventually listed on the PBS during the study period. The PBAC rejection rate of initial submissions was higher during the second half of the study period than the first.

The review found sources of uncertainly for the PBAC included aspects of clinical trial design, applicability of overseas evidence to Australia, and flaws in economic modeling.

“Some applications are based on comparisons with a standard of care in an overseas trial which may not be the standard of care in Australia. Clinical trial design is also slowly changing to accommodate smaller numbers of participants as we move towards more targeted treatments,” Dr Karikios said.

He told the limbic surveys showed almost all of his colleagues have recently discussed unfunded cancer medicines with their patients, compared to about half of medical oncologists 10 years ago.

“Most of us think it is unethical not to discuss all options – including unfunded medicines – with our patients. However the potential to cause financial harm to our patients is a new and growing issue.”

He said Australia still had the best system for public funding of medicines but better understanding of exactly why a drug was rejected would inform decision-making.

“Shifting the conversations to cost of treatment is tricky and doctors are still learning how to do it. We might be able to talk about the risk of adverse effects with a particular drug but we’re less comfortable asking patients what privately funding $5,000 per month might mean to them.”