Scientists believe they have developed a way to find unique markers within tumors, therefore making it easier for the body's immune system to turn on malignant growths and destroy them.

"This is exciting.  Now we can prioritize and target tumor antigens that are present in every cell - the Achilles heel of these highly complex cancers," said Professor Charles Swanton of the University College of London's Cancer Institute.  "This is really fascinating and takes personalized medicine to its absolute limit, where each patient would have a unique, bespoke treatment."

The new method is reported in the journal Science, which also notes that it has not been tested in patients yet and could be very expensive.  But the researchers at University College, London - whose work was funded by Cancer Research UK - believe their discovery could form the backbone of new treatments and hope to test it in patients within two years.

One of the problems the researchers will have to overcome is that cancers are not made up of identical cells.  They are a heavily mutated, genetic mess.  Samples taken at different sites within a tumor can look and behave very differently.  This is known as cancer heterogeneity. The researchers want to target the cells at the center of tumors, which act like "trunks" from which the mutations branch off.  If the immune system can be steered to attack the antigens at the "trunk" of a tumor, it will take down the branches as well.