A breast cancer cell

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 awaited the ruling by Nice.

This meant there was a "postcode lottery" over the drug, as women in one catchment area could get it, while others just a few miles away, were refused.

In Scotland more than 3,000 women are diagnosed with breast cancer each year.

Potential side effects

About half of women diagnosed with localised breast cancer will eventually develop metastatic cancer - where the cancer cells spread to other parts of the body.

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

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

Potential side effects associated with the drug include allergic-like reactions such as shortness of breath, wheezing and skin rashes.

It can also cause heart palpitations and a rapid heart beat.