Five years after Glivec received its first approval, it has become the first oncology drug to be confirmed as an effective and generally well-tolerated medicine targeting a specific cause of cancer, Swiss pharmaceutical company Novartis said.

There are about 18 patients suffering from the disease in Malta and the majority of them have been using the drug.

Glivec is a treatment for patients with a given type of leukaemia (Philadelphia chromosome-positive chronic myeloid leukaemia).

The disease is not curable without a bone marrow transplant and before the new drug was available the survival period ranged between three and five years.

Quoting data covering four-and-a-half years of use, Novartis said that about 93 per cent of newly diagnosed patients did not progress to the more advanced and terminal stages when treated with Glivec.

The five-year update from the drug's clinical trial will be presented at the American Society of Clinical Oncology meeting next month.

The company said that before Glivec was made available, about 50 per cent of patients progressed to the more advanced stages of the disease after only three to five years and the survival period was generally short.

The drug was first approved in May 2001 by the United States' Food and Drug Administration in 11 weeks, which Novartis said was the fastest FDA review period of any cancer drug at the time.

Brian Druker, the chairman of leukaemia research at the Oregon Health and Science University Cancer Institute, explained that the new drug confirms that when researchers have a precise understanding of what makes a particular cancer grow, they can target such abnormalities specifically and develop an effective, durable and well-tolerated treatment.

"After five years, we know with certainty that going after the root cause of a cancer and shutting it down not only make sense - it works," Dr Druker, who was the lead investigator of the key Glivec clinical trials, said.

Glivec is the first targeted therapy for patients with this particular leukaemia once it has been proven to inhibit the definitive cause of the disease, Novartis said.

In 2002, Glivec was also approved for gastrointestinal stromal tumours.

The drug is also being considered to treat other forms of cancer, which, while considered rare, may be life threatening and often have no approved treatments.