A new genetic test can identify breast-cancer patients who are unlikely to suffer recurrences, potentially sparing tens of thousands of women from unnecessarily undergoing chemotherapy...

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WASHINGTON — A new genetic test can identify breast-cancer patients who are unlikely to suffer recurrences, potentially sparing tens of thousands of women from unnecessarily undergoing chemotherapy, researchers reported yesterday.

The test appears to offer a solution to one of the most vexing problems in breast-cancer treatment today — deciding which women can safely forgo expensive, often-debilitating follow-up treatment — and marks one of the first tangible benefits of the massive effort to harness genetics to fight cancer, experts said.

“These study findings represent a major advance in our understanding of the role of genomics in cancer diagnosis and treatment, work that is critical to the national effort to fight cancer,” said Jeffrey Abrams of the National Cancer Institute.

The test could help many of the 50,000 to 100,000 U.S. women diagnosed each year with breast cancer that has not spread elsewhere. Many of these women undergo chemotherapy after surgery and receiving radiation, but a small proportion would suffer a recurrence with no additional treatment. The problem: There has been no reliable way to know who is at low risk.

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The new test, which measures the activity of more than a dozen genes, indicates that perhaps half of these women are at low risk of a recurrence and could forgo chemotherapy safely, researchers said.

“This is an important advance toward individualizing patient care,” said Robert Blast Jr. of the University of Texas M.D. Anderson Cancer Center in Houston. “One of the goals of contemporary oncology is to try to write prescriptions for each patient that would attack the cancer and not harm the person. In this case, it’s a question of whether to use chemotherapy.”

The $3,450 test, called OncotypeDX, was developed by researchers at the National Surgical Adjuvant Breast and Bowel Project (NSABP) in Pittsburgh, a large, ongoing federally funded research program, and Genomic Health, a Redwood City, Calif., biotech company. The Food and Drug Administration has approved the test.

To create the test, researchers sifted through some 250 genes that had been identified as playing a role in breast cancer, narrowing to 16 the candidates that appeared to be important. The researchers combined them with five noncancer genes.

Steven Shak, the company’s chief medical officer, said the firm was negotiating with insurance companies to pay for the test.

In a study to be reported in the Dec. 20 issue of The New England Journal of Medicine, researchers used the test to screen stored tumor tissue from 668 patients who had undergone treatment in the NSABP program from 1982 to 1988. All had malignancies that were sensitive to estrogen but had not spread outside the breast.

The test accurately predicted which patients were most likely to have gone on to suffer a recurrence in the next decade, with 51 percent scoring in the low-risk group, 22 percent at intermediate risk and 27 percent at high risk, researchers found. The findings correlated with the actual rates of recurrence. Only 6.8 percent of the low-risk group suffered a recurrence, compared with 14.3 percent of the intermediate-risk group and 30.5 percent of those at high risk.

The journal released the study online yesterday to coincide with a presentation at a scientific meeting in San Antonio of additional research involving 651 similar women that showed the test also could predict which women were most likely to benefit from chemotherapy.

Chemotherapy reduced the chances that women with high risk-of-recurrence scores would suffer a recurrence in the next decade by more than 70 percent, whereas treatment provided no benefit for those who scored at low risk, researchers found.

Other experts cautioned that additional research was needed to further validate the test and to pinpoint which women can use it most reliably. The test has been studied only in women who had taken the drug tamoxifen. Their tumors were dependent on estrogen, were one to five centimeters in size and had not spread to their lymph nodes.

Nevertheless, cancer specialists said, the findings represented an important advance.

“This test has the potential to change medical practice by sparing thousands of women each year from the harmful short- and long-term side effects associated with chemotherapy,” said JoAnne Zujewski of the National Cancer Institute.