The Washington University in St. Louis researchers sequenced DNA from a tumor donated by a woman in her 50s who had died of acute myeloid leukemia, an aggressive cancer that usually strikes adults. They compared the tumor DNA to DNA from the same woman's healthy skin cells. The mutations they found were not hereditary, but instead, like most cancer-causing genetic mutations, had developed over the woman's life.
One of the genetic mutations identified in the study, which was published Thursday in the journal Nature, seemed to block chemotherapy drugs from getting inside cancer cells. Four others were linked to tumor suppressing genes that normally keep tumors from developing.
"This is the first time that we've been able to look at the entire set of genes from a cancer patient, and that is key because that's going to help us understand what goes wrong," study lead author Richard K. Wilson, director of Washington University in St. Louis's Genome Sequencing Center, told ABC News.
Cancer genetics is a rapidly growing field, and recent studies have identified mutations linked to lung, brain and ovarian and breast cancers, among others. However, none of the previous studies had mapped an entire genome, instead they had looked specifically at genes researchers already suspected were linked to cancer.
"In the past, cancer researchers have been 'looking under the lamp-post' to find the causes of malignancy," geneticist Francis Collins, a former director of the National Human Genome Research Institute, told BBC News. "Now the team from Washington University has lit up the whole street."
The first complete map of a human genome, finished in 2003, took millions of dollars and 13 years to complete. But as improved gene sequencing techniques have made gene mapping faster and cheaper, it has become easier to map entire genomes. In fact, in addition to being the first cancer patient whose genome has been mapped, the anonymous patient is also the first woman.
Wilson told the New York Times that the leukemia patient's DNA will be the first of many whole cancer genomes to be sequenced. In fact, the Washington University center is already planning similar studies for breast and lung cancer.
Wilson also said that he hopes that in 5 to 20 years DNA sequencing will be as easy as popping a computer chip with a drop of blood on it into a computer.
"The ultimate hope is that you would look at someone's DNA and you'd say 'I know how to treat you based on what I found in your genes," Wilson told CBS News, "And why you are different than the patient I saw with the same disease an hour ago."