November 7, 2008 - Sequencing the Cancer Genome

All but buried by the profusion of political articles in yesterday’s newspaper was an article about a remarkable break- through in cancer research.


Working with the genes of a woman in her 50s who died of leukemia (AML), scientists at Washington University in St. Louis have sequenced the entire genome of cancer cells taken from her bone marrow, and have compared it to the genome of her healthy skin cells. This was the first time this has ever been done as a method of cancer research.

The comparative study revealed 10 separate genetic mutations present in the woman’s cancer cells, that likely had some impact on her disease: either causing her cancer or affecting her response to treatment. In an elaborate number-crunching exercise, the scientists picked these mutations out from among the 20,000 or so genes that make up the human genome. (By contrast, previous studies have searched for mutations only among 100 or so genes scientists have suspected could be involved.)

As the New York Times reports, it was a technically daunting task:

“The new research, by looking at the entire genome – all the DNA – and aiming to find all the mutations involved in a particular cancer, differs markedly from earlier studies, which have searched fewer genes for individual mutations. The project, which took months and cost $1 million, was made possible by recent advances in technology that have made it easier and cheaper to analyze 100 million DNA snippets than it used to be to analyze 100.”

This is gee-whiz technical wizardry, but – more importantly – it holds out real hope for cancer research in general. With these powerful new tools at their disposal, researchers will be able to isolate and focus in on genetic mutations that are of interest. They can then identify hitherto-unknown causes of that particular type or cancer, or create therapies to successfully defeat it.

As this technique is used to study more cancer patients, comparisons will be made between one person and another. This is expected to reveal a number of mutations that are unique to each individual, some of which could be used to create “designer drugs” to help them recover. Eventually, though – and far more exciting – a few mutations will likely turn up that are common to all patients with that type of cancer.

That is the holy grail of cancer research: a single mutation that’s responsible for causing that type of cancer. In the words of Washington University researcher Richard K. Wilson:

“Ultimately, one signal tells the cell to grow, grow, grow. There has to be something in common. It’s that commonality we’ll find that will tell us what treatment will be the most powerful.”

Exciting stuff, indeed. A reason for hope!