A mother-of-three has told a court a decision not to give her the cancer drug Herceptin is "a death sentence".
The case is being heard at the High Court
Ann Marie Rogers, 54, has been denied the drug, which is not licensed for use in the early stages of breast cancer, by Swindon Primary Care Trust.
Her legal team told the court the PCT ruling should be declared "arbitrary and unlawful".
But the trust said it was acting in line with official guidance that the drug only be used in exceptional cases.
It is the first case of its kind to reach the courts and as such is likely to set a precedent for the health service.
It targets the HER-2 protein, which can fuel the growth of breast tumours
Herceptin prevents this process happening
Around a fifth of breast cancers are HER-2 positive
It is currently licensed for use in women with advanced breast cancer - where the disease has spread within the breast or to another organ
Early stage breast cancer refers to the first occurrence of the disease
The cost for one year's treatment with Herceptin is 20,000 pounds
Herceptin has been licensed in England and Wales for the treatment of advanced breast cancer.
But pressure is mounting for the NHS to use it on patients with early stage cancer, as research has shown it is effective in fighting the disease.
Previous legal actions by women have resulted in NHS trusts backing down and funding the drug, which costs around £20,000 for a year's treatment.
Ms Rogers, a former restaurant manager from Haydon Wick, Swindon, has already borrowed £5,000 for three treatments of Herceptin, but said she cannot afford to pay for further treatments.
Philip Havers QC, representing the PCT, said while the trust had great sympathy for Ms Rogers, its actions had been "wholly in line with guidance" which states it should only be prescribed in exceptional circumstances.
He said Ms Rogers' case had been individually considered and it was concluded "no exceptional circumstances, either clinical or personal were demonstrated".
But the court was also told about an internal Department of Health letter from cancer tsar Mike Richards which said that all women with HER-2 positive early breast cancers, which includes Ms Rogers, are in exceptional circumstances.
The memo said this was his personal view, rather than government policy.
Ian Wise, representing Ms Rogers, said his client had made a statement in which she said she felt as if she had been given a "punishment like a death sentence", while her prognosis "waiting for the cancer to return is like waiting on death row".
The statement said: "I understand that there is no other treatment like Herceptin. With Herceptin, I now have a better-than-evens chance of living as opposed to a better-than-evens chance of dying.
"Herceptin has given me my life back and enabled me to look forward without having a constant fear when the cancer is coming back.
"The constant feeling that you have been given a death sentence where you simply spend your time waiting for the cancer to return has also diminished."
Mr Wise told the court the PCT's policy of restricting its use to exceptional cases was contrary to a direction from the health secretary and was "arbitrary, unlawful and irrational".
It also breached Ms Rogers's right to life under Article 2 of the European Convention on Human Rights, and the right to respect for her private life under Article 8.
Meanwhile, Roche, the drug's manufacturers, has announced it will be submitting an application to extend the licence in the next few weeks, after which NICE will fast-track its review.