THURSDAY, Feb. 6, 2014 (HealthDay News) -- Testing the entire
genetic makeup -- or all the DNA -- of tumor cells from women with
advanced breast cancer may help identify patients who could be
helped by specific treatments, according to new research.
The approach is considered the wave of the future by both the
French researchers who conducted the study and U.S. experts.
"It is possible to deliver personalized medicine," said study researcher Dr. Fabrice Andre, of the Gustave Roussy Institute in Villejuif, France. "Until now, we could [test] one gene in a large number of patients, or larger numbers of genes in a few patients."
In the new study, the researchers evaluated the whole genome --
the entire collection of a person's genes -- of more than 400
patients. The approach is much more extensive than testing for
mutations in specific genes, such as the BRCA1 and BRCA2 genetic
mutations known to raise the risk of breast cancer.
From 2011 to 2012, Andre's team evaluated the women from 18
centers in France, all of whom had breast cancer that had spread.
First they took biopsy samples. Then they conducted the
whole-genome analysis to see if they could find unique
characteristics and abnormal genes that could then be targeted for
treatment in clinical trials.
Nearly half of the patients were found to have a genetic
alteration that could be addressed with targeted treatment. Another
39 percent of women had rare alterations, many of which don't have
treatments currently available, the researchers said.
Next, the researchers matched 55 of the women with new
treatments being tested in clinical trials, targeting them to the
women's specific genetic alteration. Of those, 43 women received
the targeted treatments. And of those, four women had a response
and nine others had stable disease for more than 16 weeks, the
The study findings were published online Feb. 7 in the journal
The Lancet Oncology.
Some of the larger cancer centers in the United States are also
working on the whole-genome approach, said Dr. George Somlo, a
professor of medical oncology and therapeutics research at the City
of Hope Comprehensive Cancer Center, in Duarte, Calif. He reviewed
the findings but was not involved in the study.
"It is very expensive, very labor intensive," he said. "In the United States, the approach is evolving."
The cost of whole-genome testing varies greatly, but some
laboratories offer it for less than $10,000. Experts say the cost
will drop more in the future.
Dr. Claudine Isaacs, a professor of oncology at the Georgetown
Lombardi Comprehensive Cancer Center, in Washington, D.C., said the
approach has advantages.
"The advantage of screening the tumor either for a large battery of mutations or doing whole-genome analysis is that it gives a much broader analysis and understanding of possible patient- or tumor-specific molecular 'drivers' for that particular tumor," said Isaacs, who also reviewed the findings. "It will pick up both suspected and unsuspected [genetic] alterations."
"I do think this is the wave of the future," she said. "The hope of such an approach is to better provide our patients with a personalized approach to their care."
As promising as the approach is, Somlo said, it's important to
realize that "not every tumor needs to have whole-genome testing."
It's already known that some specific mutations or changes in
genetic activity will result in particular breast cancer patients
benefiting from targeted therapy, he said.
For instance, he said, the drug trastuzumab (Herceptin) is used
as a targeted therapy for women found to be over-activating the
protein known as HER2 (human epidermal growth factor receptor).
For breast cancer patients, the difficulty of finding an
effective treatment increases when the disease spreads, Somlo
"There are multiple mutations and the curability of those patients is very low," he said. Obtaining the genetic information in these cases would best be done as soon as possible after the cancer's spread is detected, he said.
To learn more about human genomes, visit the
National Institutes of Health.
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