The initial recommendation of the National Institute of Clinical Excellence (NICE) was to deny Glivec to all but a handful of patients with chronic myeloid leukaemia (CML).

That provoked a storm of protest from patients and doctors - and NICE, after examining favourable results of another Glivec study, changed its mind.

This is the day leukaemia patients have been waiting for

Dr Richard Sullivan, Cancer Research UK

Its final appraisal determination - which covers the health service in England and Wales - widens the circumstances under which the drug can be given.

It is already available in Scotland.

If the government, as expected, backs the ruling, many more patients are likely to receive it.

Three phases

CML accounts for one in six leukaemia cases, and mostly stems from a chromosomal defect which hinders the production of white blood cells.

There are a total of just over 2,600 people in the UK with the disease.

Glivec is the first of a new class of anti-cancer drugs, and experts estimate that it will eventually cost the NHS �25m a year to fund its use.

The original recommendation of the committee asked by NICE to look at Glivec was that only patients in what is called the "accelerated" phase should be given the drug.

We have always been clear that this means the recommendations in the final appraisal determination may differ from the provisional recommendations

NICE spokesman

This is a short phase, perhaps lasting between two and 15 months, in which signs of cancer increase more sharply as the condition gets worse after a long period of stability called the "chronic" phase.

The majority of CML patients are in the chronic phase, which lasts between three and five years after diagnosis.

Delight

NICE's early recommendation also ruled out the drug for patients in the most serious phase of the disease, the "blast crisis" phase, where their condition is worsening rapidly.

However, the final determination allows the drug for all three groups of patient, provided that other existing drugs such as interferon have been tried unsuccessfully before.

The verdict has delighted cancer campaigners.

Dr Richard Sullivan, from Cancer Research UK, said: "This is the day leukaemia patients have been waiting for.

"There is clear and extensive data to support the widespread use and funding of Glivec in this country.

"We owe it to cancer patients to ensure that breakthroughs in the labs are translated into improvements in survival and quality of life."

The latest clinical studies suggest that Glivec is highly successful at reducing the number of defective blood cells.

In chronic phase patients, 69% had what is termed a "complete response" to the drug.

Transparent process

A spokesman for NICE said that it was always possible for new evidence from scientific studies to influence the final outcome of its appraisal process.

He said: "We have always been clear that this means the recommendations in the final appraisal determination may differ from the provisional recommendations.

"As a result of the consultation and subsequent evidence the recommendations of the Committee were changed."