(BBC News) The "internal wiring" of breast cancer can predict which women are more likely to survive or relapse, say researchers.
The study shows that breast cancer is 11 separate diseases that each has a different risk of coming back.
The hope is that the findings, in the journal Nature, could identify people needing closer monitoring and reassure others at low risk of recurrence.
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Cancer Research UK said that the work was "incredibly encouraging" but was not yet ready for widespread use.