Cancer campaigners have called for clarity on who should be able to get Herceptin in the wake of a patient's failed legal challenge.
The drug is already used for advanced cancer
Ann Marie Rogers had asked a High Court judge to overturn a decision by NHS bosses not to give her the drug.
But other women in the same situation have been given the drug.
The conflict of opinions stems from the fact the drug has not yet been licensed or approved by medical authorities for use in women with early stage breast cancer.
This means that individual primary care trusts are making their own decisions about whether particular patients should be given the drug.
Cancer charities say today's High Court judgement means has not helped women to know where they stand.
Christine Fogg, chief executive at Breast Cancer Care, said: "They were hoping that the continuing confusion and fear around access to Herceptin would be resolved by this case.
"Today's decision reinforces the inequalities in accessing Herceptin that patients are suffering.
"Ann Marie Roger's case highlights yet again the urgent need for the Department of Health to give clear direction to PCT over access to Herceptin and stop the postcode lottery that sadly continues whilst we await a licensing decision."
Health Secretary Patricia Hewitt had said that PCTs should not refuse Herceptin treatment on the basis of cost.
But the High Court judge said Mrs Hewitt's comments did not amount to a direction the drug should not be refused under any circumstances.
Jeremy Hughes, chief executive of Breakthrough Breast Cancer, added: "This drug could save the lives of 1,000 women a year and it is unfair and cruel for women like Ann Marie Rogers to know that it is money and their postcode that stands between them and this potentially life-saving treatment."
Authorities say the standard licensing process must be followed in regard to Herceptin, as it would be with any other drug, to ensure its safety and benefits are proven.
The drug has already been licensed for women with advanced stage breast cancer.
But there were concerns Herceptin could increase the risk of heart failure, so more research was needed before the benefits and safety for women with an earlier stage of the disease could be assessed.
However, further studies have found the drug can halve the risk of a woman's cancer returning, if she carries the HER2 gene.
Professor Ian Smith, Head of Breast Unit at the Royal Marsden, said: "I believe that Herceptin is a very valuable drug for women with early stage breast cancer.
"Scientific evidence supports the use of Herceptin therefore I hope this judgement is not a set back for other women."
The regulation process to allow the drug to be given to women with early stage cancer is currently underway.
Roche, the company which makes it, is set to submit its application to European drugs authorites for Herceptin's licence to be extended for use with early stage breast cancer shortly.
The National Institute for Health and Clinical Excellence (NICE), which advises on the cost-effectiveness of drugs for the NHS, says it will fast-track its appraisal of Herceptin, once that license has been given.
NICE has said it hopes to issue its guidance in August this year.
Andrea Sutcliffe, deputy chief executive of NICE, said: "Once NICE issues guidance patients have equal access to effective drugs no-matter where they live.
"We will be able to issue national guidance to the NHS on the use of Herceptin within weeks of the drug being licensed for safety by the regulatory authority."
She continued: "This ruling demonstrates why it is important for NICE to assess the effectiveness of drugs and produce national guidance."
Dr Gill Morgan, chief executive of the NHS Confederation, said: "The licensing and regulatory processes are there to ensure that new drugs are both safe and effective as well as to protect patients.
"Yet PCTs find themselves under increasing public and political pressure to prescribe Herceptin off-licence - when its safety and effectiveness has not yet been proven."
'Taking a step back'
Matt Griffiths, prescribing adviser for the Royal College of Nursing, said it was important to remember that a decision in favour of Mrs Rogers would have had implications for decisions on drugs for other conditions.
"What we also need to consider is that there are other groups, such as those with mental health problems, that are not able to lobby quite as hard as others.
"We do not want drug prescribing to be determined by people power alone, but need to look at the bigger picture to ensure equity in access to medicines for all patients.
"As individuals, we would all want access to the best treatment for ourselves and our families, but, taking a step back, NICE is the right body to be deciding about treatments, balancing greater issues such as cost and clinical effectiveness."