Researchers have found that some cancer cells hide from the body's immune system using a "cloak of invisibility" so that they can spread around the body without being destroyed.
Experts at the University of British Columbia found that the chromatin - the structure containing DNA and 'histone' proteins - in some cancer cells is altered so that fewer molecular 'tags' appear on the outside of the cells.
The body's immune system normally uses cancer-specific tags to identify cancerous cells so that they can be destroyed.
However, these particular cancer cells do not have the tags on their surface and are therefore not spotted by the body's defences.
Professor Wilfred Jefferies, professor of medical genetics, microbiology and immunology and zoology at the university, said that the findings may offer "whole new avenues" for cancer treatment.
"This discovery begins to address the mysteries of how cancer hides from the immune system and spreads - it helps explain 20 years of observations in the field," he said.