Dr. Otis Brawley, chief medical and scientific officer for the American Cancer Society said that he was "delighted" by the study and anxious about unnecessary cancer treatment and the side effects that come from chemotherapy.
For women 50 or younger, chemotherapy is unwarranted for those with an Oncotype score under 16 - about 40 percent of breast cancers in this age group, the researchers said.
The researchers performed a prospective trial between 2006 and 2010 involving 10,273 women with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, axillary node-negative breast cancer.
Of the 9,717 women, 6,711, or 67 percent, had test scores indicating an intermediate risk of recurrence - their score was 11 to 25.
A recently published case study from an ongoing clinical trial has revealed an experimental immunotherapy treatment has cured a breast cancer patient. This test, called Oncotype Dx, gives a score between 0 and 100.
The Institute of Cancer Research said: "This fascinating and exciting study in a single breast cancer patient provides a major "proof-of-principle" step forward, in showing how the power of the immune system can be harnessed to attack even the most difficult-to-treat cancer". After surgery and radiation, those women were randomly assigned to receive chemotherapy with an estrogen-blocking medication or just the estrogen hormone blocker.
Scientists found that giving hormone therapy alone was as good as the combination of chemotherapy and hormone therapy in women with the intermediate score.
However, these are the results from a single patient and much larger trials will be needed to confirm the findings. The women in the "unfavourable" range had to receive chemotherapy.
One of the patients texted the program 1,217 times.
Certain women 50 or younger did benefit from chemo; slightly fewer cases of cancer spreading far beyond the breast occurred among some of them given chemo, depending on their risk scores on the gene test.
About 41,000 women and 465 men died from the disease that year.
'What that test does is look at 21 different genes to see if each is turned on or off and then if it is over-expressed or not. These women should discuss chemotherapy with their doctors, the researchers said.
Knowing a patient's recurrence risk can spare them from enduring chemotherapy, but also can direct them towards it if they discover that they are at a higher risk, Sparano says.
Perkins hopes she's cured - a word she is nearly afraid to utter - but knows that the cancer "could come back tomorrow". Nine-year rates were similar for iDFS (83.3% vs 84.3%), DRFI (94.5% vs 95.0%), RFI (92.2% vs 92.9%), and OS (93.9% vs 93.8%) for the RS 11 to 25 arm. The test, which has been on the market for several years, analyzes the activity of 21 genes to predict a woman's risk of recurrence over 10 years.
The 49-year-old woman had been selected for the novel therapy after chemotherapy failed to stop a tumor in her right breast from growing.
"Oncologists have been getting much smarter about dialing back treatment so that it doesn't do more harm than good", said Steven Katz, a University of MI researcher who examines medical decision-making.
The type of hormone therapy administered was dependent upon whether women were premenopausal or postmenopausal-91% of postmenopausal women received an aromatase inhibitor-based regimen, whereas premenopausal women were most commonly prescribed either an endocrine therapy regimen comprising either tamoxifen alone or tamoxifen followed by an aromatase inhibitor (78%).