Cancer researchers say they have taken an important step in the effort to understand the disease.  For the first time, they have decoded the complete DNA of a cancer patient and traced her disease to its genetic roots.  VOA's Carol Pearson has more.

Researchers at Washington University used malignant blood cells from a woman who died of acute myeloid leukemia, a cancer of the blood forming cells in bone marrow.

There has been little change in the treatment for this disease for years because doctors did not understand how it formed.

Dr. Richard Wilson and other researchers compared the genes from the woman's cancer cells to those of her healthy skin cells. "This is the first time that we've been able to look at the entire set of genes from a cancer patient," Dr. Wilson said. "And that's key because that's going to help us understand what goes wrong."

The researchers identified ten genetic mutations, or changes, in the cancer cells.

One of the mutated genes blocks chemotherapy drugs, four others appear to disable the mechanism in a cell that prevents it from turning into a cancer cell.

"If those genes are mutated or de-activated, there's a very good chance the cancer can start to grow out of control," Dr. Wilson said.

Researchers are now working to identify the genetic mutations that can cause other cancers.

They hope a simple blood test will enable them to identify every cancer patient's genetic makeup.

Oncologist Dr. Ross Levine says he expects the research to transform the way cancer patients are treated, "[It will help in] Deciding which patients should get which treatment, which patients need more treatment," Dr. Levine said. "Which patients are more likely to have their cancer come back."

Scientists also say learning the genetic makeup of a particular cancer patient will help them develop new, more targeted drugs and save more lives.