Genetic Test Shows Promise in Guiding Breast Cancer Care
TUESDAY May 10, 2011 -- Scientists have developed a new, albeit preliminary, genetic test that seems to predict which breast cancer patients can benefit from specific types of chemotherapy.
That, in turn, could greatly help guide treatment, according to a study in the May 11 issue of the Journal of the American Medical Association.
The findings are exciting but need to be replicated, said one expert, Dr. Iuliana Shapira, director of cancer genetics at Monter Cancer Center and assistant professor of medicine at Hofstra University North Shore Long Island Jewish Health System in Lake Success, NY. She was not involved in the study.
According to the study's lead author, Dr. W. Fraser Symmans, gene-based tests such as the Oncotype DX are already in wide used to help guide breast cancer care. That test can help predict a patient's chance for breast cancer recurrence, but only if they have estrogen-receptor-positive breast tumor and are treated with hormone therapy, said Symmans, who is professor of pathology at the University of Texas MD Anderson Cancer Center in Houston.
Based on the results of Oncotype DX, "patients with low risk might [be able to] avoid chemotherapy," he said.
The new study looked at a newer "genomic predictor" of breast cancer treatment response and survival for women with newly diagnosed, invasive breast cancer. The study was based on tumor samples taken from 310 patients with HER2/neu-negative breast cancer who were treated sequentially with two chemotherapy drugs, taxane and anthracyline, both common components of breast cancer chemotherapy.
If the tumors were estrogen-receptor (ER)-positive (meaning their tumors responded to estrogen), the women were also treated with hormonal (endocrine) therapy.
The new test appeared to be effective in predicting outcomes: 92 percent of the women that the test predicted would respond to this chemotherapy did, in fact, survive three years without a relapse, giving them an 18 percent lower risk of dying compared to those identified as "non-responders" to the treatment.
And, Symmans said, "at three years, breast cancer had not returned in 97 percent of women with ER-positive and 83 percent of women with triple-(ER) negative breast cancer if they were predicted to be treatment-sensitive. If they were predicted to be treatment-insensitive, the rates were 86 percent and 57 percent, respectively."
The study was funded by Susan G. Komen for the Cure and the U.S. National Cancer Institute, among others. Several of the authors also hold patents with Nuvera Biosciences, Inc., which was involved in the test.
"This study is not the definitive final word on the subject, but it offers a totally new way of looking at the question of how do we predict whose tumor is really sensitive to chemotherapy, whose tumor is probably resistant to chemo or neither of the above," said Symmans.
One expert called the study just one "baby step" on the path towards more individualized treatments for patients. "I don't know if this is enough to propel people to use this," said Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City.
The test, while promising, is "not ready for patients," agreed Dr. Massimo Cristofanilli, professor and chairman of medical oncology at Fox Chase Cancer Center in Philadelphia. Nor does it predict which therapy will be best, he added.
But depending on further research, the test may one day be valuable in helping women and their doctors make difficult decisions regarding treatment, as opposed to today, when so much is guesswork. "It's important to me to not give to have to give 100 women chemotherapy to save 10 or 15 lives," Shapira explained. "It's important to me to be able to identify the 10 or 15 patients who are going to benefit from chemotherapy."
There's more on treatments for breast cancer at the U.S. National Cancer Institute.
Posted: May 2011
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