Sydney, Nov 23 Australian scientists have successfully developed the first test in the world for a technique by which cancer cells make themselves immortal.

The advance, made by researchers at the Children's Medical Research Institute, could speed up development of new types of anti-cancer drugs.

It could also lead to blood screening for early detection of some aggressive tumours and to monitor the effects of treatment.

Whenever a cell divides, its telomeres - a region of repetitive, protectetive DNA at the end of a chromosome - slightly wear away. The telomeres become shorter and shorter due to constant cell division and the consequent wear and tear and ultimately the cell dies.

However, cancer cell multiply constantly and prevent their telomeres from erosion and thus live forever.

"Both mechanisms are prime targets for the development of new anti-cancer treatments," the Sydney Morning Herald quoted Roger Reddel, director of the Children's Medical Research Institute, as saying.

About 85 per cent of cancers use an enzyme called telomerase, which Professor Blackburn co-discovered in 1984, to rebuild their telomeres.

Almost 15percent cells like some breast and lung cancers use a mechanism called alternative lengthening of telomeres, or ALT to stay alive indefinitely.

Prof Reddel said: "Ultimately, we would like to find drugs that turn the ALT mechanism off."

However, Jeremy Henson found that cancer cells using the ALT procedure create tiny circles of DNA. The number of these DNA circles is linked to the strength of the ALT mechanism.

Prof Reddel added: "They provide a very sensitive and rapid indicator of ALT activity," Professor Reddel said.

The study will help in the development and use of drugs that can turn off the ALT and kill the cancer cells.

The team also discovered that some ALT using cancers drop these circles into the bloodstream thus making it quite possible to detect cancer early through a blood test.

The discovery has been described in the journal Nature Biotechnology (ANI)