For the first time, scientists have managed to decode the complete DNA sequence of a cancer patient.

The researchers used cells donated by a woman in her 50s who died of acute myelogenous leukemia, a cancer of blood-forming cells in the bone marrow. The researchers applied the sequencing technique to map all the genes in her tumor cells and to compare them with the genes from a normal cell from the patient. This technique allowed them to see the differences between healthy DNA and the DNA of cancer.

The Washington University team identified 10 gene mutations that were associated with the blood cell cancer. Just two of the identified genetic alterations were associated with this form of cancer before. Eight were new genetic mutations that were never linked to this kind of cancer before. They found that almost all the cells in the tumor sample had nine of the gene mutations.

"We found mutations in genes that make a lot of sense when normal cells become cancer cells," said study senior author Richard K. Wilson, director of the Washington University Genome Sequencing Center, in St. Louis. The same techniques can also be used to study other types of cancer.

"This is the first human cancer genome that's been sequenced. In the past, we've always looked at parts of the genome for mutations. But this is the first time that we've been able to look at everything," says author Timothy Ley, a professor of medicine and genetics at the Washington University School of Medicine in St. Louis.

The team at Washington University center has already started genetic sequencing of a second patient with this form of leukemia. His genome is already in progress, the team said. It’s possible that the scientists may find that there are dozens of different genes that contribute to this type of cancer. The gene mutations differ from one patient to another. "This suggests that there is a tremendous amount of genetic diversity in cancer, even in this one disease," said lead researcher Dr Richard Wilson.

After mapping enough cancer genomes, researchers will have an image of the genetic mutations that can make a cell malignant. All these efforts may someday make it possible to perform genome sequencing for all cancer patients, which will be the key to better diagnostic tools and cancer treatments in the future.

Myelogenous leukemia is a common form of cancer that affects blood and bone marrow. Leukemia has long been the subject of numerous studies and experiments; up to this point, however, the results haven’t been that good. Each year in the United States, nearly 8,800 people die of AML. About 13,000 new cases of acute myelogenous leukemia are diagnosed in the United States each year. The researchers chose to study this disease because it is severe and the treatment has not improved in decades.

Scientists hope the map may eventually lead to the discovery of better treatments, new diagnostic tests and new drugs to cure the disease.

The findings were reported in the November 6 issue of the journal Nature.