A team at the Institute of Cancer Research in Britain claims the breakthrough may lead to the first new drugs in as little as five years` time, despite the preliminary nature of the research, the `Daily Mail` reported.
During their five-year study, the scientists studied the DNA of 104 breast cancer patients, including many Britons, to identify the three genes. One of the three genes, C6ORF211, drives the growth of tumours, and is most likely to be focus of drug research, they say.
All of the women studied had something known as oestrogen receptor-positive breast cancer, which accounts for four in five of all breast tumours. It got its name because oestrogen "feeds" and fuels the tumour by latching onto proteins on the surface of cancer cells known as receptors.
Many existing treatments work by cutting off this oestrogen supply. But tumours frequently become resistant to treatment, allowing the cancer to return after surgery or spread throughout body -- with potentially fatal consequences.
The sex hormone`s key role in the process means that the genetics of the oestrogen receptor have been intensively studied for decades. So, the scientists were stunned to find the DNA near it harboured three previously unknown genes.
Dr Anita Dunbier, the study`s lead author, said: "We found the genes in a place we thought we knew a lot about -- it is like finding gold in Trafalgar Square. It seemed too obvious to be true. We had to check things very thoroughly to make sure it wasn`t just a false discovery.
"We now have to look further at how these genes work but the discovery could lead to possible new therapies that will benefit women with breast cancer in the near future."
Importantly, despite the genes` proximity to the oestrogen receptor, they work separately from it. This means that new treatments could work where existing ones fail, say the scientists.
Dr Dunbier said: "What we hope to do is unlock the door to more treatment options."
Creating new drugs from scratch can take years but the research team hopes to speed up the process by testing medicines that are already on the market for other illnesses.
Dr Dunbier said: "There could be things out there already that were designed for something else and could target this. The next step will be to screen various compounds to see if any of them have an effect."
Added team member Prof Mitch Dowsett said: "This research is exciting because it shows that while the oestrogen receptor is the main driver of hormonal breast cancer, there are others next door to it that also appear to influence breast cancer behaviour."
The findings have been published in the latest issue of the `PLoS Genetics` journal.