A woman who today began a landmark legal battle to get the breast cancer drug Herceptin on the NHS said a decision to deny her the medication amounted to "a death sentence".

Ann Marie Rogers is challenging Swindon primary care trust (PCT) in the first court case against a decision not to provide the drug, which is said to halve the chances of the aggressive Her2 form of breast cancer recurring.

Today, Ian Wise, appearing for Ms Rogers, asked a judge to declare "arbitrary and unlawful" the PCT's policy of only providing Herceptin in "exceptional cases".

Mr Wise told Mr Justice Bean, sitting in London, that Ms Rogers had said in a statement she felt "as though I have been given a punishment like a death sentence".

Ms Rogers, who has "a 57% chance of her breast cancer recurring in 10 years", also stated that "waiting for the cancer to return is like waiting on death row". She added: "I know that if it comes back it will be terminal."

Ms Rogers, 53, a former restaurant manager from Swindon, has already borrowed £5,000 for Herceptin treatments but says she cannot afford to fund further courses. If the mother-of-two wins her case, the NHS could be forced to pay for the £22,000-a-year drug for hundreds of women with breast cancer.

The case is the first of its kind to reach court after other primary care trusts, faced with threats of legal action, agreed to fund the treatment.

Mr Wise told the court that Swindon PCT's policy of restricting the use of Herceptin to exceptional cases was contrary to a direction from the health secretary, Patricia Hewitt, and was "arbitrary, unlawful and irrational". The PCT's decision also created "a postcode lottery" in the prescription of the drug, he said.

He asked the court to quash the PCT's decision, to order it to continue funding Ms Rogers' current course of treatment and to continue to provide her with Herceptin while it was medically appropriate to do so.

At a hearing just before Christmas, a judge ordered the trust to fund her treatment until the outcome of this week's hearing.

Mr Wise said: "As clinicians inform us, if the cancer does return, it is uniformly fatal. Both the claimant [Ms Rogers] and her clinician believe Herceptin gives her the best chance of survival. There is no evidence from any specialist in the field which does not support the use of this treatment for women who fit the eligibility criteria."

Herceptin is only licensed for advanced stages of the disease, but pressure has mounted on NHS trusts to provide it to women with early stage breast cancer after high-profile challenges.

A BBC survey, published yesterday, found that three-quarters of cancer doctors are allowed to prescribe the drug for early stage breast cancer despite it not being licensed.

The Panorama poll of 390 oncologists in England and Wales found slightly more than one-quarter were always allowed to prescribe the drug by their NHS trusts and half were able to do so sometimes.