Breast cancer is effectively ten different diseases, according to breakthrough research that could revolutionise treatment.
The biggest study of its kind in the world has classified the country’s most common cancer into ten separate types.
The finding brings doctors closer to the holy grail of tailoring treatments to individual women. The rewriting of the rule book on breast cancer could also lead to new drugs and better diagnostic tests.
Dr Julia Wilson, of Breakthrough Breast Cancer, said: ‘This is incredibly exciting research which has the potential to change the face of breast cancer; from how we diagnose and treat it, to how we follow it up afterwards.’
However, the need for more research means it will be three to five years before women with breast cancer can start widely reaping the benefits of the shake-up in treatment.
Despite great strides being made in breast cancer in recent years, the disease is still one of Britain’s biggest killers, claiming the lives of almost 1,000 women a month. And, with almost 50,000 new cases a year, it is the country’s most common cancer.
When a woman is diagnosed, her tumour is classified into one of four types, simply by looking at tissue from it down a microscope. This provides a guide as to how long a woman is likely to survive and which drugs will be effective.
But the system is far from infallible, with some treatments failing unexpectedly and other women surprising doctors by beating a supposedly extra hard-to-treat tumour.
The latest study, detailed in the prestigious journal Nature and funded by Cancer Research UK, helps explain why.
The painstaking analysis of the genetics of 2,000 tumours, including many from women in London, Cambridge and Nottingham, has revealed there to be ten sub-types of the disease. Each tumour within a particular group shares similar genes and different women with the same type have similar odds of survival.
The ‘exquisitely detailed’ analysis also revealed several new genes that drive the growth and spread of the disease. This opens the door for the development of drugs that counter their effects. Knowledge of the genetics of each type of the disease will also speed the development of drugs, allowing women to have treatments tailored to their tumour. A handful of such ‘wonder-drugs’, including Herceptin, are already in use.
The breakthrough could also speed the search for an especially hard-to-treat form of breast cancer known as ‘triple-negative’.
It also helps explain why around 5 per cent of women who have the most common form of the disease and should have a relatively good prognosis do very badly. Cambridge University’s Professor Carlos Caldas, the study’s co-leader, said: ‘We are failing these women. They are a prime target for new trials that try to identify better treatments.’
Perhaps just as importantly, the study, which was done in collaboration with Canadian researchers, could spare some women unnecessary treatment. Knowing how to target drugs better will mean that those with a tumour type that is easier to treat will be spared gruelling therapies that provide no extra benefit.
The need for more research means the first tests are three to five years from widespread use. Development of new drugs will take even longer.
However, the results will change the way clinical trials for new treatments and drugs are run, so some women will benefit within months.
Dr Harpal Kumar, chief executive of Cancer Research UK, said the study was the culmination of decades of research.
He said: ‘This really changes the way we think about breast cancer – no longer as one disease but actually as ten quite distinct diseases, dependent on which genes are switched on and which ones aren’t for an individual woman.
‘This research will help us make a much more accurate, much more precise, diagnosis for every patient.
‘That will enable us to make sure that we really target the right treatment to the right woman based on those who are going to benefit, or if they’re not going to benefit, not exposing them to the side-effects associated with those treatments. There is huge reason to be optimistic about what is going to happen.’
The charity Breakthrough Breast Cancer said the research could ‘revolutionise’ treatment.
Head of research Dr Julia Wilson said: ‘In essence the entire patient journey could change. This is another important building block in our goal for women to receive tailor-made treatments specific to their particular type of breast cancer.’
Baroness Delyth Morgan, chief executive of Breast Cancer Campaign, said: ‘Being able to tailor treatments to the needs of individual patients is considered the holy grail for clinicians and this extensive study brings us another step further to that goal.’