A breakthrough by British scientists could help attack the root cause of cancer in the same way that weeding helps your garden.
The research could speed up attempts to wipe out cancer by targeting tumour stem cells that drive the disease.
A team from Oxford University has developed a new method of isolating cancer stem cells that can then be grown and studied in the laboratory.
The technique could pave the way to developing drugs that attack cancer at its root.
Dr Trevor Yeung, from the Weatherall Institute of Molecular Medicine at Oxford University, said: "Cancer stem cells drive the growth of a tumour. If we could target treatments against these cells specifically, we should be able to eradicate cancer completely."
Until now research on cancer stem cells has been slow, since the cells are difficult to identify and isolate from tumours.
In the past scientists have tried to find cancer stem cells in tissue samples taken from patients.
The new research involves better ways of using molecular markers to identify cancer stem cells, and maintaining the cells in simple laboratory cultures.
Instead of using biopsy samples, the scientists worked with established bowel cancer cell lines.
They found that the proportion of cancer stem cells within different bowel cancers varies widely, with aggressive tumours containing higher numbers.
The research is reported today in the journal Proceedings of the National Academy of Sciences.
Dr Yeung said: "Radiotherapy and chemotherapy work against all rapidly dividing cells. But there is increasing evidence that cancer stem cells are more resistant than other cells to this treatment. Cancer stem cells that have not been eradicated can lead to later recurrence of cancer.
"It's like trying to weed the garden. It's no good just chopping off the leaves, we need to target the roots to stop the weeds coming back.
"People have assumed that cancer stem cells made up a small proportion of the cells in a tumour, but it is becoming increasingly clear that this is not correct. The most aggressive tumours can have a majority of cells that are cancer stem cells."