Tags: dna | breast | cancer | gene

Decoding DNA Boosts Cancer Care

Tuesday, 12 June 2012 01:03 PM

Decoding the DNA of patients with advanced breast cancer may one day allow scientists to identify distinct cancer "signatures" that help predict which women are most likely to benefit from certain therapies, a new study suggests.
In a report published in the journal Nature, researchers at Washington University School of Medicine in St. Louis said they have uncovered genetic mutations in breast cancer patients that are linked to whether or not they will respond to estrogen-lowering therapy. They also found the mutations may be clues to how likely breast tumors are to grow quickly and spread.
The research -- which also involved physicians and scientists at the Alvin J. Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine and The Genome Institute -- involved analyses of the DNA from 77 post-menopausal women with stage 2 or 3 of what’s known as “estrogen-receptor-positive breast cancer,” the most common form.
"This is one of the first cancer genomics studies to move beyond cataloging mutations involved in cancer to finding those linked to treatment response and other clinical features," said researcher Elaine Mardis, co-director of The Genome Institute. "If our results are validated in larger studies, we think genomic information will be one more data point for physicians to consider when they select among several treatment options for their patients."
In women with this form of breast cancer, estrogen fuels the growth of tumors, and patients typically receive drugs known as aromatase inhibitors to lower estrogen in the body. But the drugs only work in some women.
For the new study, researchers compared the DNA in the tumors to DNA from the same patients' healthy cells, which allowed them to identify mutations that only occurred in the cancer cells. Twenty-nine of the tumor samples came from women who were resistant to aromatase inhibitors, and 48 came from patients whose tumors responded.
The scientists found tumors in women who responded to the estrogen-lowering drugs had few mutations, while those whose cancers were resistant to the treatment had higher mutation rates.
"This makes sense in hindsight but it's not something that we would have predicted," Mardis said.
"As a medical oncologist, I'm looking for clues for how to best treat my patients with breast cancer," said lead researcher Dr. Matthew Ellis, MD, who treats patients at the Siteman Cancer Center and Barnes-Jewish Hospital. "We're just beginning to see that many patients only have mutations that occur in low frequency. Targeting these mutations should be a focus of new clinical trials."
The study was funded, in part, by the National Institutes of Health.

© HealthDay

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Gene tests may help doctors determine which breast cancer patients will benefit most from therapies.
Tuesday, 12 June 2012 01:03 PM
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