Scientists at Cancer Research UK have found out how cancer cells bypass the body’s safety checks making them virtually “immortal”, a discovery that could lead to new cancer treatments.

They discovered that cancer cells made copies of spare DNA from elsewhere in the genome to replace telomeres, found at the end of chromosomes. Telomeres shorten each time the cell divides and, upon reaching a critical length, triggering the cells in-built expiry date.

In 85% of cases, cancer cells bypassed this by reactivating telomerase, an enzyme capable of rebuilding telomeres.

A study in yeast cells highlighted possible ways in which the remaining 15% of cells stop this process. Researchers deleted the gene that codes for telomerase in yeast cells, which would usually cause telomeres to be lost and exposed chromosome ends to fuse. A small number of cells, however, didn’t fuse, suggesting another strategy to protect themselves had been found.

Dr Helen George, head of science information at Cancer Research UK, said that the discovery raised the possibility that drugs could be developed to restore these cells to their natural lifespan and halt the growth of cancers.