Ms Clark has given the NHS a deadline of 30 September

Barbara Clark, 49, from Bridgwater, has been denied Herceptin by the Somerset Coast Primary Care Trust (PCT).

The trust said it was operating within national guidelines, which makes the drug available only to patients in the advanced stages of the disease.

But Ms Clark said she would go to the High Court if the trust did not change its decision by the end of September.

The guidelines on Herceptin prescription are set down by the National Institute for Clinical Excellence (NICE), which says it will issue guidance on its use in early breast cancer "...as close to the drug being licensed for this condition in the UK as possible".

Its chief executive, Andrew Dillon, said the European Agency for the Evaluation of Medicinal Products (EMEA) had yet to assess whether Herceptin is a safe treatment for women with early breast cancer.

Once a drug is licensed, we expect PCTs to take full account of the available evidence when reaching funding decisions Rosie Winterton Health minister

"Until they do this, it can't be licensed for general use in the UK. The EMEA can only start work when a manufacturer applies for a license, or asks for a license on an existing drug to be extended."

The drug's manufacturer, Roche, has previously said it is likely to apply for a licence in 2006. A licence may granted within two or three months of the application.

Recent trials have shown that Herceptin could be highly effective in increasing the life expectancy of women in the earlier stages of the disease.

NICE has agreed to fast-track a review of the drug for newly-diagnosed patients, but it could be another year before a decision is made.

Ms Clark said: "That could be too late, I could be dead within seven months.

House for sale

"It's just appalling they're hanging on. This has been an uphill struggle for me while I'm on chemotherapy."

Ms Clark has put her home on the market and launched a campaign to raise the �30,000-a-year it would cost to buy the drug privately.

A statement from the trust said: "Somerset Coast PCT wishes to give detailed consideration to the correspondence received... and would therefore prefer not to comment until it has done so."

Health minister Rosie Winterton said the preliminary results on the use of Herceptin for early breast cancer were "encouraging", but added: "More work needs to be done to be certain that the benefits of this treatment for this group of patients outweigh any potentially damaging side effects.

"Once a drug is licensed, we expect PCTs to take full account of the available evidence when reaching funding decisions.

"With record funding going into the NHS, where the evidence is very strong there is no reason to believe a PCT would refuse funding."