Herceptin has been available in the US for almost five years, and women in many European countries can also get it.

However, it was not licensed for use in the UK until June 2001, and the National Institute for Clinical Excellence, which advises the government on the clinical and cost-effectiveness of drugs, is only now ready to deliver its judgement.

A breast cancer cell
	The battle for Herceptin: Some hospitals and health authorities pay for the drug It costs �10,000 per patient per year  Read about how two women fought to get Herceptin

The delay has caused a storm of protest from patient groups - and patients themselves, many of whom have been forced to pay for the treatment, which costs at least �700 a week.

Some health authorities and hospitals chose to pay for it, while they waited for the ruling by NICE.

This means there is a "postcode lottery" in the drug, as women in one catchment area can get it, while just a few miles away, they are refused.

Herceptin is given to women who have advanced breast cancer, and trials suggest it can hold up the progress of the cancer, as well as improve quality of life.

One-in-five

Approximately one-in-five women in this position are suitable for treatment - a blood test can identify those who are.

We have been waiting 18 months to find out if Herceptin will be made available to those who will benefit

Delyth Morgan, Breast Cancer Breakthrough

If NICE rules in favour of the drug, then the government has the final say in whether the NHS should pay for it, but has pledged to implement all NICE guidance in full.

NICE only covers England and Wales, and separate guidance will have to be issued for Scotland and Northern Ireland.

Paying for Herceptin would cost the NHS tens of millions of pounds each year.

Breast cancer is the most common cancer in the UK with over 35,000 new cases diagnosed in the UK alone each year.

It is the leading cause of all deaths in women aged 35 to 54 as it kills more than 1,000 women every month.

Delyth Morgan, the chief executive of charity Breast Cancer Breakthrough, said: "We have been waiting 18 months to find out if Herceptin will be made available to those who will benefit.

"We hope very much that the news will be good as this will have enormous implications for women with advanced breast cancer."