It's being suggested National's cancer drug funding promise has put Pharmac in a difficult position.

If elected, the party will allocate $280 million over four years, to fund 13 treatments including for lung, bowel, melanoma and kidney cancers.

It would be funded by restricting fee-free prescriptions to superannuitants and those on low incomes.

Medical oncologist Chris Jackson told Mike Hosking this is the first time a political party has told Pharmac what to fund.

He says they're asking for these chosen drugs to be funded first, leap frogging every other patient group.

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