After almost 20 years of research, Vlodavsky has cloned a gene instrumental in the spread of the cancer. He and his team of Israeli researchers have now begun to use that advance to develop a method to stop cancerous cells in their tracks.

``Chemotherapy and radiotherapy... attack every cell that proliferates and therefore have some side effects,'' Vlodavsky said.

``Here we are talking about something a little more sophisticated, something that is directed against a specific phenomenon in tumour progression.''

Whether from a breast tumour or a skin malignancy, cancer cells invade the body by infiltrating blood vessels to transport themselves to healthy tissue and organs.

The immune system destroys cancer cells that stay in the blood for too long. So to survive and spread, cancer cells need to break through thevessel walls and escape from the bloodstream if they are to accomplish their deadly mission.

Vlodavsky says they do this by drilling through blood vessel walls using an enzyme called heparanase, which he discovered in 1983.

Vlodavsky and his partner, the Israeli biotechnology firm, Insight, have isolated and cloned the gene responsible for heparanase, and are now looking for ways to counteract the enzyme.

His findings, along with the results of research by a team of Australian scientists, have been published in the current issue of the journal Nature Medicine.

``The tumour cells have the opportunity to go into the blood and once they are in the blood they can spread all over and get to the target organ, (a process) which we call metastasis,'' Vlodavsky said.

``Actually metastasis is the reason why cancer is so dangerous and why so many people die from it. Not because of the primary tumour, which can be removed in surgery, but because of its spread to organs like the brain and kidneys,'' hesaid.

Vlodavsky believes that if scientists can neutralise the heparanase enzyme, the cancer cells will be trapped in the bloodstream and destroyed before they can cause damage.

Although there are other enzymes that help cancer spread, Vlodavsky says his team's research at the Hadassah Hospital here shows that heparanase is one of the most crucial.

Mice injected with cancer cells died in the laboratory within a set period of time. But when an agent that inhibited heparanase was administered, the life-span of the mice was prolonged significantly.

Their research could result in radical cancer treatments in the form of gene therapy or drugs that disarm heparanase and keep cancer localised.

`This is an important lead,'' said cancer expert Lance Liotta by telephone from the National Cancer Institute in the United States.

In the meantime, Insight is developing diagnostic kits to detect the presence of early-stage cancer by looking for traces of heparanase in patients' urine.

``We can look for levelsof this protein in the urine of patients, in the plasma... we can already see signs that we can detect higher levels correlated with the progression of the disease,'' Vlodavsky said.

Insight has acquired US patents on the process for cloning the gene responsible for heparanase and for a range of possible applications, and is now filing for international patents.

Vlodavsky said that if heparanase is suppressed along with other enzymes involved in the spread of cancer, there is a chance that in the future, cancer could become ``a manageable disease'' like diabetes.

Vlodavsky warned that his work was still at the level of basic science and said it could take at least five years for a drug to be developed.

Until then, the race to combat heparanase is on.