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 the expensive and 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 who are diagnosed each year with breast cancer that has not yet spread elsewhere in the body. Many of these women undergo chemotherapy after getting surgery and radiation. But only a small proportion would actually suffer a recurrence if they had no additional treatment. The problem has been there is no reliable way to know who is at low risk.
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 safely forgo chemotherapy, researchers said.
"This test can identify 50 percent of patients who have an excellent prognosis and most likely don't need chemotherapy," said Soonmyung Paik, who led the research. "They can be spared from unnecessary chemotherapy. This can make a big difference in how we treat patients."
The new test stems from the global effort to decipher the human genetic code and understand cancer on a molecular level, which has raised hopes that scientists will create a new generation of more precise tests and more potent, less toxic, "targeted" treatments tailored to individual patients.
"This is an important advance toward individualizing patient care," said Robert C. 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 Inc., a Redwood City, Calif., biotech company. The Food and Drug Administration has already approved the test.
To create the OncotypeDX test, researchers sifted through 250 genes that had been identified as playing a role in breast cancer, narrowing the candidates to 16 that appeared to be important because of their effects on activities such as regulating cell growth and hormone sensitivity. The researchers combined them with five non-cancer genes.