Breast cancer rules rewritten in 'landmark' study
The study in Nature analysed breast cancers from 2,000 women.
It will take at least three years for the findings to be used in hospitals, BBC News reports.
Cancer cartography
Researchers compared breast cancer to a map of the world. They said tests currently used in hospitals were quite broad, splitting breast cancer up into the equivalent of continents.
The latest findings give the breast cancer map far more detail, allowing you to find individual "countries".
"Breast cancer is not one disease, but 10 different diseases," said lead researcher Prof Carlos Caldas.
He added: "Our results will pave the way for doctors in the future to diagnose the type of breast cancer a woman has, the types of drugs that will work and those that won't, in a much more precise way than is currently possible."
At the moment, breast cancers are classified by what they look like under the microscope and tests for "markers" on the tumours.
Those with "oestrogen receptors" should respond to hormone therapies such as tamoxifen; those with a "Her2 receptor" can be treated with Herceptin.
The vast majority of breast cancers, more than 70%, should respond to hormone therapies. However, their reaction to treatment varies wildly. Prof Caldas said: "Some do well, some do horribly. Clearly we need better classification."
Unprecedented scale
His team looked at frozen breast cancer samples from 2,000 women at hospitals in the UK and Canada.
They looked in huge detail at the genetics of the tumour cells - which genes had been mutated, which genes were working in overdrive, which were being shut down.
Details also at http://www.bbc.co.uk/news/health-17740690
