During a conversation I had with a doctor a couple of years ago, the subject of cancer diagnoses came up, in a tangential way. She said that not all that many decades ago, a physician who had established that a patient had cancer often wouldnt bother investigating further: since there werent any effective treatments for any kind of cancer, there wasnt much point in finding out what kind of cancer it was. You could try to cut it out, or you could leave it in and see what happened, and that was about it.

Now, of course, that has changed. It matters what cancer you have, because different cancers respond differently to different treatments. As we get better at treating the disease, it pushes us to get better at differentiating them; as we establish the various kinds, it allows us to target drugs more precisely at the ones they work on, so that the drugs themselves become more effective. There is a virtuous circle between diagnostics and treatment that improves both. Thats why the news that the NHS is to open 11 major genomics centres with more to follow around the country is so hugely positive.

Over the past few years, genomics the study of our genetic code has taken off in spectacular style: while it took decades and billions of pounds to sequence the first human genome, now the information in a human cell can be catalogued in a few days for about a grand. This, obviously, opens up huge possibilities for medicine. It renders it practical to record and analyse the genetic code of thousands of people, and to see how small differences in our DNA change our vulnerability to different diseases.

And thats exactly what the NHS plan, with Genomics England, involves. The centres will take the genetic data of 100,000 people, all suitably anonymised, and analyse and record them, making them available to researchers at universities and drug firms. They will also sequence the DNA of 25,000 cancer sufferers, and the DNA of the cancers themselves. Cancer is a disease of the genes the product of mutations which send the cell into uncontrolled reproduction and establishing which genes are vulnerable to which mutations will be vital in defeating its various incarnations.

This has possibilities far beyond cancer, though. To a startling degree, we are freed from the crippling burden of infectious disease. Thats not the case in developing countries, where more than half of all deaths are caused by infection, according to the World Health Organisation; but in the rich West, nearly nine out of 10 of us will die of a non-communicable disease, when something simply goes wrong with our bodies. Sometimes that something goes wrong because of environmental factors smoking, drinking, obesity and sometimes were just unlucky, but our risk of suffering pretty much any non-communicable disease, from heart disease to diabetes to stroke, is influenced by our genes. If we can see which genes tend to be associated with which diseases, doctors can help those at the greatest risk to take steps to avoid it.

An obvious example is breast cancer, which oncologists now think of as at least 10 different diseases. While the average lifetime risk for a woman in the UK is about 12.5 per cent, according to Cancer Research UK, if they have a particular mutation in a gene called BRCA1, that risk goes up to between 60 and 90 per cent. Angelina Jolie was tested and found to have this mutation, and chose to have a double mastectomy as a preventive measure. Less dramatically, statins could be prescribed specifically to those people who are found to be more susceptible to high blood pressure or heart disease, instead of as now giving them to a huge swath of the population in order to help the minority who actually need them. It is the difference between a sniper rifle and a shotgun.

The trick with the genomics revolution will be tying it in to the everyday business of health care in England, and that is where these centres will become vital. When doctors are able to look at a patients genetic information as easily as they can their height and weight, they will be able to target those patients with the interventions that will work best on them true individualised medicine. But that involves making genome sequencing routine, calming understandable fears about privacy, and convincing people to take that first scary step and look at what their genes hold in store for them.

A year or so after my conversation with the doctor about cancer, a close relative was diagnosed with malignant melanoma. It was a horrible, terrifying time. Skin cancer comes in various forms, many of them relatively benign, but melanoma is a killer. And until recently there were no drugs that were effective against it. If caught early, it could be cut off, and you were usually all right; later, once it had got into your system, you were in real trouble. Like the cancers a century ago, there was little point knowing more about what kind of melanoma it was, because you couldnt do much about it.

Luckily (touch wood) my relatives cancer was caught early, and the prognosis is good. But if, heaven forfend, it comes back, there are now drugs that can be used, with some success and the choice of which drug depends on your genes. The genomic revolution is already transforming medicine, and saving the lives of people right now. This is an extraordinary time for medicine.

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Genomics: the revolution that's transforming medicine

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