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BETHESDA, Md. -- The National Cancer Institute on Tuesday launched a new study using "molecular profiling" to help better predict which early-stage breast cancer patients are likely to benefit from chemotherapy and which are not.
Researchers plan to enroll 10,000 U.S. and Canadian women who have been diagnosed with breast cancer that has not spread to lymph nodes and is sensitive to the hormone estrogen.
More than half of the 212,920 U.S. women expected to be diagnosed with breast cancer this year fall into that group, said Sheila Taube, associate director of the cancer institute's Cancer Diagnosis Program. According to current practice guidelines, 80% to 85% of these women should get chemotherapy as well as surgery and hormonal therapy, Taube said at a science writers seminar at the National Institutes of Health. But even if they skip chemo, their estimated 15-year survival rate is 70%, she said. "Most of the patients are going to do very well without it."
The trick is identifying who those patients are. For that, the new trial will use a diagnostic test called Oncotype DX, on the market since 2004. It measures the expression of 21 genes involved with breast cancer. For example, the estrogen receptor gene is linked to a more favorable prognosis, while the HER2 gene is linked to a less favorable outcome.
The test provides women with a "recurrence score" of zero to 100. The lower the score, the less likely a woman will have a recurrence. Also, a study posted online Tuesday by the Journal of Clinical Oncology found that the higher a woman's recurrence score, the more likely she is to benefit from chemotherapy. That study, by the National Surgical Adjuvant Breast and Bowel Project, used banked tumor specimens from 651 patients who took part in a previous study comparing tamoxifen with a placebo.
In the new study, women with a score of less than 11, or an estimated 29% of study participants, will get hormonal therapy. Those with a score above 25, an estimated 27%, will receive chemotherapy plus hormonal therapy. And those in the middle, for whom uncertainty about treatment remains, will be randomly assigned to hormonal therapy and chemotherapy or hormonal therapy alone. The women will be studied for 10 years, with an additional follow-up of up to 20 years.
Steven Shak, chief medical officer of Oncotype DX maker Genomic Health and a co-author of the clinical oncology journal paper, says about 3,000 U.S. patients opted for the test in the first three months of this year. An increasing number of health plans, including Medicare, now cover the $3,460 test, Shak said.
"However, the RS (recurrence score) is only a beginning," the cancer institute's Sandra Swain writes in an editorial accompanying the study on the journal's website.
As technology improves and larger tumor banks become available for analysis, scientists will be able to further fine-tune their ability to predict recurrences and tailor treatments, she writes. "This will allow us to forgo unnecessary treatment in a large number of patients without denying treatments to patients who can most benefit from it."
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