Scientists have known there are many biological pathways that lead to breast cancer.
But their road-map had many gaps. This latest research fills in many of them, opening the possibility of entirely new personalized treatments.
The research is part of a giant federal project to analyze the thousands of changes in the DNA of cells that lead to all kinds of cancer.
It also provides the strongest evidence that breast cancer is not one disease, but four major types, and many subtypes.
This means that some drugs already on the market to treat leukemia, melanoma, lung and other cancers might treat some breast cancer and offers clues for developing entirely new drugs.
Doctors who treat women with breast cancer say they their patients need to know that while while today's results are exciting, clinical trials are still needed, and those are likely years away
"This isn't something that all can take action on tomorrow in the clinic, but it is how we are going to put together our next round of therapies and how we're going to forward to change this disease," said Dr. Jennifer Litton.