By Nick Triggle
BBC News health reporter
The NHS has been put in an impossible position by Health Secretary Patricia Hewitt's intervention over early breast cancer drug Herceptin, officials say.
Research has shown Herceptin can reduce the risk of tumours returning
Ms Hewitt questioned a ruling by Stoke local health bosses not to fund the drug for a patient and after mounting pressure they reversed the decision.
But officials told the BBC no trust could now refuse to fund the drug, which is unlicensed for early cancer.
The health secretary said it was still up to local health chiefs to decide.
Herceptin has been licensed in England and Wales for the treatment of advanced breast cancer.
But pressure has started mounting for doctors to use it on patients with early stage cancer as research has shown it is effective in fighting the disease.
The UK drugs regulator is still waiting for Herceptin's makers to submit an application.
The situation reached boiling point this week when North Stoke Primary Care Trust refused to fund the treatment for Elaine Barber, a Staffordshire mother-of-four who is in remission but has been warned her cancer may return, on grounds of safety and cost.
On Tuesday, the 41-year-old threatened to take legal action and Ms Hewitt said she was concerned and demanded to see the evidence up on which the PCT made the decision.
Within a day, North Stoke had reversed their decision, citing Ms Barber's "particular exceptional circumstances".
The move was welcomed by cancer charities and Ms Barber.
But others within the NHS believe the trust was left with no option and has left all trusts toothless if patients come forward in the future demanding the drug.
One PCT chief executive told the BBC: "After the health secretary took that position, the trust had no option. It was between a rock and a hard place.
"I don't think any trust will be able to say no to Herceptin now, even if there are legitimate concerns about safety and cost. No trust would be foolish enough."
And Nigel Edwards, director of policy at the NHS Confederation, added: "PCTs now find themselves placed under huge public pressure if they do not prescribe Herceptin for use in early stage breast cancer.
"We are concerned that primary care trusts are being put in an almost impossible position."
But Ms Hewitt, who last month had said no trust should deny Herceptin on financial grounds alone, denied a precedent had been set.
She said: "It will still be up to PCTs to decide."