Cancer experts are disputing a Pharmac claim that New Zealanders' access to cancer drugs compares well with Australia.
They are also demanding that the drug-buying agency speed up its assessment of a medication that may cure melanoma in some patients.
The Pharmac study, published early this month, said 88 cancer medicines were funded in both countries.
The 22 drugs that are funded in Australia but not New Zealand did not offer health gains that would be considered clinically meaningful by international cancer experts, it said.
The assessment has gone down badly with local specialists, who said they supported Pharmac and its work but the analysis was biased.
Cancer Society medical director Chris Jackson said, "It's very clear to all oncologists in New Zealand that we do not have the same level of access to cancer drugs as people do in Australia.
"It's very clear that the gap is much bigger than presented in the Pharmac report and we would like to see a robust and externally validated analysis of the true situation. And if Pharmac won't do it, we will."
Some of the 88 drugs used on both sides of the Tasman were funded for more uses in Australia, he said.
Herceptin, for example, was funded for breast cancer in New Zealand but both breast and stomach cancer in Australia.
The Pharmac report measured the benefit of the drugs New Zealand did not have in a narrow way, whereas a different European method of comparison known as the European Magnitude of Clinical Benefit would have rated these drugs more highly.
The melanoma immunotherapy drug Ipulimumab, which was not funded in New Zealand, was another good example, he said.
"The Pharmac analysis would tell you that that drug is not a useful drug, it shouldn't be funded but, in actual fact, Australia has said it's worth funding, the UK have said so, Canada have said so, and a much more sophisticated analysis would look at the fact that a third of the patients get extraordinary benefit and would take that into consideration."
Pharmac is defending its research, which was commissioned from Sapere in March, and intended as a "snapshot".
Medical Director John Wyeth said: "What we are saying is we have a range of cancer drugs funded in New Zealand which are giving us the best health outcomes for the amount of funding that we have available.
"There are differences in access to cancer drugs between Australia and New Zealand - that is highlighted in our report.
"The key message, however - what we're looking for is the best health outcomes and we believe that the differences are not having a detrimental effect."
The European Magnitude of Clinical Benefit Scale method of comparison that cancer specialists wanted to be used would have entailed a major rework and significant delay, he said, but the plan was to review the report, possibly with a different method of assessing clinical benefit.
Cancer specialists worried in particular about a lack of effective treatments for the skin cancer melanoma.
Richard Martin is an Auckland melanoma surgical oncologist, who speaks for Melanoma New Zealand and the Melnet group of more than 750 health professionals working with melanoma.
"I think the report has to be looked at with some reservation, simply because it is slightly biased and there's a definite spin being put on this."
Dr Martin said new drugs had also been funded in Australia since the Pharmac report was released.
"Therefore we feel that the playing field has changed significantly since this report, and therefore, we would like them to look at these new melanoma drugs much quicker."
The lack of access to promising new melanoma drugs was hard for patients with advanced disease, he said.
A drug called Dicarbazine, for instance, which has been used since the 1960s in New Zealand, is ineffectual for stage four melanoma, he said.
"We're seeing people on a weekly basis who are in a desperate situation with metastatic melanoma, and the fact that they're being offered a drug that doesn't work when they know and we know that there are a number of new melanoma drugs that are very effective, and certainly will prolong their disease-free interval, and also probably prolong their life, in many cases as well."
He said Pharmac must speed up its assessment of costly new drugs like pembrolizumab, or Keytruda.
Pharmac agreed there were no effective funded treatments for melanoma currently but said there were interesting new developments which were being considered as quickly as possible.