Published in the international science magazine "Nature" the research unpicked practically all genetic errors that cause healthy breast tissue to go rogue.
The international team of scientists looked at all 3 billion letters of genetic code - the entire blueprint of life - in 560 breast cancers and uncovered 93 sets of instructions, or genes, that if mutated, can cause tumors.
Scientists expect this to be the definitive list, barring a few rare mutations. Cancer Research UK said the findings were an important stepping-stone to new drugs for treating cancer.
Devil in the detail
"There are about 20,000 genes in the human genome. It turns out, now we have this complete view of breast cancer - there are 93 of those [genes] that if mutated will convert a normal breast cell into a breast cancer cell. That is an important piece of information," according to Professor Mike Stratton, director of the Sanger Institute in Cambridge, who led the research.
He said the mutated genes and their proteins are targets for new therapeutics. Targeted drugs such as Herceptin are already being used by patients with specific mutations.
A (slow) step forward
Stratton expects new drugs will still take at least a decade to reach patients. The study has brought researchers closer to getting a complete picture of the genetic changes at the heart of breast cancer and the key biological processes that go wrong in cells and drive the disease.