A major study published in the New England Journal of Medicine is providing the best evidence to date that a 21-gene test done on the tumor can identify breast cancer patients who can safely avoid chemotherapy.
Oncologist Kathy Albain, MD, FACP, FASCO of Loyola University Medical Center and Loyola University Chicago Stritch School of Medicine is among the main co-authors of the international multicenter trial. Dr. Albain also is a member of the trial's steering committee.
The test examines 21 genes from a tumor sample to determine how active the genes are. The tumor then is assigned a score between 0 and 100; the lower the score, the lower the chance the cancer will recur in distant organs if treated with only a pill such as tamoxifen. In previous studies involving fewer patients, a low score also suggested that chemotherapy does not work well and does not add to the survival benefit of tamoxifen.
The clinical trial enrolled 10,253 women, including 41 at Loyola, who had a certain type of breast cancer (hormone-receptor positive, HER2 negative) that had not spread to lymph nodes. Although the lymph nodes were not involved, the tumors had other features that indicated chemotherapy should be given, followed by tamoxifen or other endocrine therapy pills.
In the trial, women whose tumors scored 10 or lower on the 21-gene test received standard hormone therapy such as tamoxifen, but did not undergo chemotherapy. After five years of being followed closely, there was a less than a 2 percent risk the cancer had spread to nearby or distant sites. The five-year overall patient survival was 98 percent.
These findings, researchers concluded, provide the highest level of evidence that the multigene test can spare the use of chemotherapy in women with low-scoring tumors who otherwise would receive chemotherapy. "This should provide a lot of reassurance to women and their physicians," Dr. Albain said. "In women whose breast cancer scored low on the multigene test, there was outstanding survival with endocrine therapy alone. The test provides us with greater certainty of who can safely avoid chemotherapy."
In the trial, 15.9 percent of the women had a multigene test score of 10 or lower. An additional 68 percent had a mid-range score of 11 to 25. These women were randomly assigned to receive either hormone therapy plus chemotherapy or hormone therapy alone. Continued follow-up still will be needed to determine whether any women in this larger group, with tumors in the intermediate-score range, can safely forgo chemotherapy.
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