Tom Chivers During a conversation 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 wouldn't bother investigating further: since there weren't any effective treatments for any kind of cancer, there wasn't 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.

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There is a virtuous circle between diagnostics and treatment that improves both. In Britain, it was announced this week that the NHS is to open 11 major "genomics centres" with more to follow.

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 dollars to sequence the first human genome, now the information in a human cell can be catalogued in a few days for about two 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 that's 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. 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. Western nations are now freed from the crippling burden of infectious disease. That's 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 we're just unlucky, but our risk of suffering pretty much any of those non-communicable conditions, 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 them.

The trick with the genomics revolution will be tying it in to the everyday business of health care. When doctors are able to look at a patient's 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.

The genomic revolution is already transforming medicine, and saving the lives of people right now. This is an extraordinary time for medicine.