We should be able to avoid having some of the marked side effects that some patients experience

Lauren Rivory

This test could mean patients who processed the drug more quickly could be given more to maximise their chance of benefiting from it.

But a person who breaks down the drugs more slowly, could be treated with a small amount of the drug.

It is particularly crucial to get the right dose of the toxic chemotherapy drugs as they can cause severe side-effects.

Laurent Rivory, who was part of the research team, said: "With this test, we should be able to avoid having some of the marked side effects that some patients experience, while at the same time we should be able to increase the doses to more effective levels in those that rapidly eliminate drugs."

Breakdown

The Australian research is being carried out by the Sydney Cancer Centre and the University of Sydney.

It looks at how fast patients break down an antibiotic called erythromycin in the liver.

In the test, the patient is injected with a tiny dose of erythromycin, which has a very small dose of radioactivity "tagged" onto it.

Its high time we started thinking in more detail about the individual treatment of cancer patients

Professor Roland Wolf

The antibiotic is broken down, and the radioactivity is released in a form of carbon dioxide gas.

This is caught in the balloon as it is breathed out, and measured for radioactivity.

If a small amount of radioactivity is produced over a long period of time, it shows doctors the patient cannot break down the drug, and others like it, very well.

However, those who produce a large quantity of radioactivity which disappears very quickly process the drugs well.

'Potential'

Although the test, which has been used in other areas of medicine, is not effective for the way all anticancer drugs are processed by the metabolism, doctors estimate 50-60% of chemotherapy drugs are broken down in this way.

The team is also looking at how the presence of cancer in the body seems to affect how patients to break down drugs.

Professor Roland Wolf, director of biomedical research at the University of Dundee and Honorary Director of the Imperial Cancer Research Fund molecular pharmacology unit, said further investigation of this test was essential.

Professor Wolf and his team are looking at how the body responds to anticancer drugs, concentrating on a particular form of an enzyme in the liver which is involved in the elimination of drugs from the body.

He said: "I think its high time we started thinking in more detail about the individual treatment of cancer patients, both in terms of the type of cancer, the biochemistry of that particular tumour, and of the particular patient."

Kate Law, head of clinical trials for the Cancer Research Campaign said: "This test has the potential for making chemotherapy less harmful for people, and for making the cure rate better by giving them the optimum dose."