Some cancer sufferers are spending large sums of money on expensive drugs that will not extend their life, a specialist says.
Professor Richard Sullivan, the director of the Institute of Cancer Policy at Kings College in London, has been in New Zealand for a conference.
He said many of the most expensive cancer drugs simply did not do what they said they would.
For example, some could shrink the cancer itself but do nothing to extend the life of the patient.
"Some drugs are coming with enormous uncertainty about what sort of benefit they really deliver to patients ... but huge price tags.
"Countries and people are being asked to pay a great deal of money for the unknown and a lot of that unknown doesn't pan out.
"When we look backwards over sort of two or three years we discover the drugs actually don't work."
Dr Sullivan said some of the treatments he sees being promoted are simply quackery.
He said it was a very complicated picture for individual cancer patients because some drugs would improve quality of life but would not necessarily extend their life.
Very good quality palliative care could also be life extending and the idea of having great numbers of medical interventions may not be right for that patient, he said.
Dr Sullivan said cancer drugs are a crucial part of the way patients were treated and it was very important for countries to negotiate the price of cancer drugs.
"The US pay absolutely astronomic prices because they're simply not hard enough in negotiating the prices down.
"You have to put in place really strong mechanisms in your country to control prices, negotiate good prices."
Dr Sullivan supports banning drug advertising that targets patients.
In New Zealand, drug advertising to consumers is allowed, but it is banned in Europe.
"I'm completely in favour of keeping the direct consumer advertising ban," Dr Sullivan said.
He said a clear message from the conference was that it was important to develop and deliver a cancer action plan for New Zealand.
The difficulties included working out the priorities and what to tackle first, adequate funding and ensuring there was integrated care across the country.