New research has examined breast cancer in even more detail

The emotion and anxiety aroused by a single word – ‘cancer’ – spans ages, sexes, nations, races and classes.

But as we understand more about the disease, the idea that cancer is a single, common enemy, is increasingly being challenged.

In late 2009, the publication of the first complete cancer genomes showed the extraordinary chaos present in the DNA inside cancer cells. But they also highlighted the molecular differences between different types of cancer – in this case, skin cancer and lung cancer

Other large gene studies have revealed even more differences between types of cancer, but have also increased out understanding of the differences between the ‘same’ cancer type in different people – the foundation of ‘personalised medicine’.

For example, last week a team of Canadian and British researchers, writing in the journal Nature, analysed the DNA from 104 ‘triple-negative’ breast cancers – a particularly hard-to-treat form of the disease.

As this in-depth post on the Respectful Insolence blog describes, they found that no two women’s cancers were alike – there were differences across all the tumour samples. Even a subcategory like ‘triple-negative’ breast cancer doesn’t seem to be a single disease (a point we’ll return to later). And genetic differences also appeared between cells from the same tumour – known as ‘intratumour heterogeneity’.

This point was emphasised a few weeks earlier by researchers at our London Research Institute. They analysed multiple samples from the same patient’s kidney tumour and secondaries (where the cancer had spread to other parts of the body).

No two samples were identical, suggesting that there’s significant variation even inside a tumour. As we discussed in this blog post, it looks like tumours can be highly varied, creating new challenges in the search for personalised medicine.

A video about METABRIC (click to open in a new window)

Which brings us to today’s news, of a landmark Cancer Research UK-funded study published in Nature.

Through intricate genetic analysis, the same British and Canadian researchers, led by Professor Carlos Caldas from our Cambridge Research Institute and Professor Sam Aparicio from the British Columbia Cancer Centre in Canada, have uncovered crucial new information about breast cancer.

Their study group, METABRIC (Molecular Taxonomy of Breast Cancer International Consortium), looked at the patterns of molecules inside tumours from nearly two thousand women, for whom information about the tumour characteristics had been meticulously recorded.

They compared this with the women’s survival, and other information, like their age at diagnosis.

While many other studies have highlighted differences between cancers, the METABRIC study looked at so many tumours that they could spot new patterns and ‘clusters’ in the data.

Their conclusion is that what we call ‘breast cancer’ is in fact at least ten different diseases, each with its own molecular fingerprint, and each with different weak spots.

This is simultaneously daunting and heartening – daunting because each of these diseases will likely need a different strategy to overcome it; and heartening because it opens up multiple new fronts in our efforts to beat breast cancer.

Let’s look at the background to the study, then in detail at what the researchers actually did, what they found, and what this means for the future of breast cancer treatment and diagnosis.

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