Gene test determines if breast cancer patients can avoid chemo

Chemotherapy isn’t necessary in every case of cancer, but it’s often hard to decide when a patient should undergo the treatment. Frequently, the notion is better safe than sorry, but in many cases this can lead to unnecessary time and money spent, emotional and physical strain, and can actually cause a new cancer to grow (albeit rarely).
However, thanks to a major study published in the New England Journal of Medicine, there is now strong evidence that a gene test can determine which breast cancer patients can safely avoid chemo, according to a press release.
The gene test examines 21 genes taken from a sample of a tumor. Using this information, the test is able to determine how active the genes are—meaning how hard they work to spread the cancer—by assigning an activity level between 0 and 100. A lower number indicates that chemo may be less necessary, as it signifies that the cancer is less likely to spread only if it’s treated with hormone pills like tamoxifen.
Previous studies also indicated that chemotherapy would not work as well in those with low scores, and that it does not add any additional survival benefits to hormone therapy. However, these studies involved fewer patients than the current study, which enrolled 10,253 women with a certain kind of breast cancer known as hormone-receptor positive, HER2 negative cancer. So it wasn’t certain whether the results would be replicated.
In the 10,000 women, the tumors had not yet spread to the lymph nodes, but had features that generally meant they should be given chemotherapy paired with endocrine therapy pills (like tamoxifen).
Low scores mean good news
After the women were given the gene test, those with scores of 10 or lower—about 15.9% of the women—received the standard hormone pill therapy, but did not undergo chemo. Another 68% fell into the mid-range scores of 11-25, and were randomly assigned either hormone pills alone or pills with chemotherapy.
These women were monitored closely for five years. The mid-range group received minimal benefits as compared to the normal statistics, but the low-range group showed significant improvements. They had a less than 2% risk of the cancer spreading to local sites. Further, their five-year survival rate was 98.7%—almost 5% higher than the average survival rate for this kind of cancer (93.8%).
“This should provide a lot of reassurance to women and their physicians,” said co-author Kathy Albain, MD, FACP, FASCO of Loyola University Medical Center and Loyola University Chicago Stritch School of Medicine. “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.”
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