Breast cancer treatment could be revolutionized with patients offered more accurate diagnoses and better-targeted treatments after a study in which scientists genetically charted the disease. The research found that rather than being a single disease, breast cancer can be classified into 10 distinct types. It also identified several new genes that determine the aggressiveness of the cancer.
For the study the team of researchers examined 2,000 tumours in the largest ever genetic study of breast cancer tissue. They found they could help predict patients' chances of survival more accurately and this could lead to the development of more effective drugs for each cancer type. The research by Cancer Research UK scientists, published in science journal Nature on Wednesday, will not have an immediate impact on sufferers.
Dr Harpal Kumar, chief executive of Cancer Research UK, said, “This is a landmark study that really changes the way we think about breast cancer – no longer as one disease but actually as 10 quite distinct diseases, dependent on which genes are switched on and which ones aren't for an individual woman.” The study, by researchers in the UK and Canada, showed that all the different ways the cells changed when they became cancerous could be grouped into 10 different categories - named IntClust one to 10.
Kumar added, “What this research will help us to do is make a much more accurate, much more precise, diagnosis for every patient with breast cancer in the future. 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. That will enable us to make much more progress in breast cancer in coming years.”
Lead researcher Professor Carlos Caldas, at the charity's Cambridge Research Institute, said, “We have a completely new way of looking at breast cancer. It's not going to change the outcome for patients treated in the NHS tomorrow. But it will change the way we do clinical trials with new avenues to develop targeted treatments.” He added that this would help scientists to understand why some women with breast cancer have a much better prognosis than others, but cautioned that more research would be needed. “This is a first, very important step,” he said.
He added that scientists now understood what tumors look like at a molecular level and will eventually know which drugs each of the 10 cancer subtypes will best respond to. “We need to carry out more research in the laboratory and in patients to confirm the most effective treatment plan for each of the 10 types of breast cancer,” he said.
There are clear survival differences among the 10 categories of breast cancer. Clusters two and five seem to have a 15-year survival of around 40%. Clusters three and four have around 75% survival over the same period. This could help better inform patients. In terms of treatments, there is bad news. There is a targeted therapy for just one of the 10 breast cancers groups. That is Herceptin, which is already used in a targeted group of patients. Other groups will still have "standard" therapies such as chemotherapy or radiotherapy. The hope is that by identifying the 10 breast cancers it will be possible for researchers to design drugs for each one, but that is still a work in progress.
Baroness Delyth Morgan, chief executive of the 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 nearer that goal.”
Till date breast cancer had been classified into four subgroups, depending on what they look like under the microscope and on tests for positive or negative “markers” on the tumors. Those with estrogen receptors should respond to hormone therapies such as tamoxifen, while those with a Her2 receptor can be treated with the drug Herceptin. More than 70% of breast cancers should respond to hormone therapies. But reactions to treatment vary widely.
The Health Secretary, Andrew Lansley, has already described the promise of the field as “immense”. There is a long way to go, as only one of the 10 breast cancer categories has a personalised treatment at the moment. But as is so often the case, breast cancer research is leading the way. “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.” He said the charity would begin using the new criteria in clinical trials it funded.
A Department of Health spokesperson said, “We are always looking at new ways to improve outcomes for cancer patients and that is why we are investing more than £750m to make sure people are diagnosed with cancer earlier and have better access to the latest treatments. We look forward to seeing the future results of this ongoing work and will continue to work with Cancer Research UK to find the best possible way to improve outcomes for people with breast cancer.”
Breast cancer is now the most common cancer in the UK. Eight out of 10 women now survive breast cancer for more than five years, compared with five out of 10 in the 1970s. It will take at least three years for the findings to be used in hospitals.
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