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Scientists decode set of cancer genes
(Agencies)
Updated: 2008-11-06 11:41

Until now, Dr. Wilson said, most work on cancer mutations has focused on just a few hundred genes already suspected of being involved in the disease, not the 20,000 or so genes that make up the full human genome.

The earlier research has uncovered many mutations and led to the development of a few so-called targeted drugs, which treat some cancers by homing in on specific defects in the cells. Examples include the drug Herceptin, for women with a certain type of breast cancer, and Gleevec, for a type of leukemia and a rare gastrointestinal cancer.

So the older approach is useful, Dr. Wilson said. But he added, "if there are genes mutated that you don't know about or don't expect, you'll miss them."

Indeed, 8 of the 10 mutations his group found in the leukemia patient had never been linked to the disease before and would not have been found with the more traditional, "usual suspects" approach.

But researchers have debated which method is best.

"We had a lot of people who said it was a stupid idea to sequence the whole cancer genome," Dr. Wilson said, noting that a private donor had paid for most of the study and that the National Cancer Institute had chipped in relatively little, and only after the work was well under way. However, the cancer institute did pay for preliminary work and is now supporting research to decode more cancer genomes.

A cancer expert not involved with the study, Dr. Steven Nimer, chief of the hematology service at Memorial Sloan-Kettering Cancer Center, called the research a "tour de force" and the report "a wonderful paper." He said the whole-genome approach seemed likely to yield important information about other types of cancer as well as leukemia.

"It is supporting evidence for the idea that you can't just go after the things you know about," Dr. Nimer said.

He added: "It would be nice to have this kind information on every patient we treat."

Dr. Nimer also predicted that oncologists would quickly want to start looking for these mutations in their patients or in stored samples from former patients, to see if they could help in predicting the course of the disease or selecting treatments.

Studying cancer genomes has become a major thrust of research. In the past few years the government has spent $100 million dollars for genome studies in lung and ovarian cancers and glioblastoma multiforme, a type of brain tumor. But that project, The Cancer Genome Atlas, has not decoded an entire genome. So far, it has identified mutations in brain and lung cancers, also reported in Nature in September and October. One discovery is expected to affect medical practice -- a mutation that can cause some patients with the brain cancer to get worse instead of better if they are given a common chemotherapy.

The person who gave her cells for the study at Washington University became not only the first cancer patient, but also the first woman to have her entire genome decoded. Her information will be available only to scientists and not posted publicly, to protect her privacy and that of her family. The only other complete human genomes open to researchers so far have come from men, two scientists known for ego as well as intellect, who ran decoding projects and chose to bare their own DNA to the world: James D. Watson and J. Craig Venter. Their genomes are available for all to inspect.