Until recently, breast cancer had been dealt with as one disease, but a new study of 2,000 women suggests that it should be thought of as ten different strains.
New categories may improve treatment and survival rates, as drugs will be far easier to tailor to every individual patient’s needs.
The study in medical journal Nature has compared breast cancer to a map of the world, saying that the research now means they are able to make out and differentiate between different “countries” (or strains) of the disease.
While this is being hailed as a “key moment”, it will take at least three years for changes to be noticed in hospital.
Lead researcher Prof Carlos Caldas said of the findings, "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."
Cancer Research UK funded the research, and Dr Harpal Kumar from the charity added, "This is the largest ever study looking in detail at the genetics of breast tumours.
"This will change the way we look at breast cancer, it will have an enormous impact in the years to come in diagnosing and treating breast cancer. We think this is a landmark study."