A recent survey suggested Herceptin is still rationed

Health Secretary John Reid has demanded to know why some health authorities are reluctant to prescribe drugs that are recommended nationally.

It comes as a government report suggests NHS cancer services have improved over the past three years.

It shows death rates are falling and more cancer specialists are now working in the NHS.

Cancer deaths

Deaths from cancer in people under the age of 75 have fallen by 10% since 1995, the report says.

However, it also reveals that unskilled workers are twice as likely to die from cancer compared to professionals.

I think this is a clear signal that the secretary of state won't tolerate postcode prescribing Joanne Rule CancerBACUP Two sides of the Herceptin lottery

This is largely because they are more likely to smoke and less likely to eat fruit and vegetables.

The report says the NHS is making progress in tackling this problem.

Mr Reid said while improvements have been made more needs to be done.

"Patients are now beginning to see improvements - shorter waiting times, better access to doctors, new equipment. But the government is not complacent," he said.

The report comes just days after doctors warned that the NHS is actually failing cancer patients.

The Royal College of Radiologists said a lack of staff and essential equipment mean some patients are dying needlessly and others are living in unnecessary pain.

It also follows a survey by the charity CancerBACUP, which suggested many women are being denied a key drug to fight breast cancer.

It found that 61% of women in the South West had access to Herceptin but only 14% could get it in the Midlands.

The charity estimated that 1,000 women were missing out on the drug, even though the government's drugs watchdog, the National Institute for Clinical Excellence, has recommended it for all women with advanced breast cancer.

Nice has made similar recommendations for 16 other cancer drugs and there is a strong suspicion that many patients are also being denied these drugs.

Postcode prescribing

Mr Reid has asked the government's cancer tsar Professor Mike Richards to carry out an investigation to find out if patients are being denied cancer drugs.

"We need to make sure that money is getting through to the front line, and that proven drugs and treatments are available everywhere in the country to those who can benefit from them," he said.

"Where they are not, I will be seeking rapid action to redress the situation."

Joanne Rule of CancerBACUP welcomed the move.

"I think this is a clear signal that the secretary of state won't tolerate postcode prescribing."

Peter Cardy, chief executive of Macmillan Cancer Relief, said: "It is vital that the government makes its record investment count for patients."

The Association of the British Pharmaceutical Industry welcomed the move but warned that "postcode prescribing" is not confined to cancer drugs.

"It is clear that a review is needed to look at where and why this is happening," a spokesman said.

Opposition parties criticised the government's record on cancer services.

Shadow health secretary Liam Fox said: "Serious problems remain, and responsibility for many of these rest with ministers.

"Most shockingly, average waiting times for cancer patients have risen significantly."

Liberal Democrat health spokesman Paul Burstow said: "The government still has a long way to go to close the health divide in this country.

"The fact that unskilled workers are far more likely to die of cancer than their professional counterparts is a measure of that divide."

Delyth Morgan, chief executive of the charity Breakthrough Breast Cancer, said: "Patchy services, delays in diagnosis and the availability of breast cancer drugs have knocked public confidence in the NHS.