The breast cancer drug Herceptin is set to be licensed for use in early stage disease by European regulators.
The drug is already used for advanced cancer
A formal announcement about the drug, which could help some women with the disease, is expected to be made by the European Commission next week.
The NHS drugs watchdog has pledged it will then complete its fast-track appraisal of the drug "within weeks".
The National Institute of Health and Clinical Excellence will rule if the drug is safe and cost-effective.
Last month, it was announced a committee at the European Medicines Agency (EMEA) had recommended the approval of Herceptin in a record 27 days.
The process to license the drug for early stage breast cancer began in February when manufacturers Roche submitted its application to the European authorities.
The drug is already used in the UK to treat women with advanced breast cancer.
But there has been pressure to use the drug to treat women with an earlier stage of the disease.
A year's course of the drug, which targets the HER-2 protein which can fuel the growth of breast tumours, costs around £20,000.
Around a fifth of breast cancers are HER-2 positive.
Appeal Court ruling
Herceptin has been the subject of high profile legal battles by women seeking access to the drug.
In April, Ann Marie Rogers of Swindon, Wiltshire, won an Appeal Court ruling which, while it did not force primary care trusts to fund the drug, said it would be irrational to treat one patient and not another.
However lawyers argued the judgment still left the door open for primary care trusts to refuse to fund Herceptin if they provided a rational argument.
Health Secretary Patricia Hewitt intervened in the debate last October to say NHS bodies should not withhold the drug on cost grounds from patients whose doctors had recommended it.
However, there have been concerns that Herceptin's effectiveness is over-hyped
'Wealth of evidence'
Andrew Dillon, chief executive of NICE, said: "Our appraisal of the clinical and cost effectiveness of Herceptin is already underway.
"We are keen to ensure that guidance is available in a matter of weeks."
Barbara Clark, 50, from Bridgwater, Somerset, who won her case to receive the drug on the NHS last October, welcomed the EMEA's decision.
She said: "I feel this is the end of a tremendous fight. It's great news."
Jeremy Hughes, chief executive of Breakthrough Breast Cancer, said: "This is great news and should persuade any hesitating doctor or PCT to offer Herceptin to suitable patients.
"The full license confirms that Herceptin is safe and effective in early breast cancer.
"The wealth of evidence available together with this licensing decision, will reassure those who were previously cautious about prescribing a drug that wasn't licensed for early breast cancer."
Joanne Rule, chief executive of Cancerbackup, said: "Breast cancer patients across England and Wales are currently experiencing a dreadful postcode lottery; denied Herceptin because of where they live or how 'exceptional' their lives are deemed to be.
"This can stop now."