Normally, old or damaged cells are sent a chemical message to stop dividing and self-destruct to prevent any mutations being duplicated and growing into tumours.

Cancer cells usually ignore these messages and continue to multiply indefinitely and out of control.

An enzyme called telomerase is one of the factors responsible for protecting cancer cells from the natural ageing process.

Now a team funded by the Cancer Research Campaign has developed a way to "switch off" the enzyme.

Researcher Professor Robert Newbold, of Brunel University, West London, said: "We already know that telomerase is active in around 85% of cancers and is probably responsible for kick-starting the process that protects cancer cells from dying.

"However, our latest research has finally been able to pinpoint a new way to potentially de-activate this rogue enzyme."

In laboratory tests, groups of healthy genes carried on chromosomes were transferred into breast tumour tissue to ascertain which combination could potentially stop the gene that produces telomerase from working.

Professor Newbold said: "We have now identified chromosome 3 as the specific group of genes which has the ability to stop the further production of telomerase in breast tumours.

"By using advanced genetic techniques we have also been able to map the gene responsible to a small region of the chromosome."

The introduction of a normal copy of chromosome 3 into the breast cancer cells causes them to regain their normal ageing process and die.

Synthetic production

Cancer Research Campaign made the breakthrough

Scientists will now be working on ways to mimic this group of genes.

It is hoped this will lead to the synthetic production of anti-cancer drugs to block telomerase and halt the growth of human tumours.

The CRC Director General, Professor Gordon McVie, said: "This research really is a major step forward in the hunt for new and improved treatments for breast cancer patients.

"It is also another example of how gene therapy is being developed to target tumours without causing damage to healthy cells as well."