Groundbreaking clinical trial shows that most women with early stage breast cancer can now safely avoid chemotherapy treatment after surgery, chronic pains and even death that comes with it.
The study which features four studies deemed to have the greatest potential to impact patient care, found no improvement in disease-free survival when chemotherapy was added to hormone therapy.
This group estimate more than 123,000 women in the US and 23,000 women in the UK with the particular form of cancer each year.
The findings will have an immediate impact on about two-thirds of women in clinical practice, sparing thousands of women the side effects of chemotherapy.
The study, enrolled 10,273 women, of those, 6,711 were randomly assigned to receive hormone therapy alone or hormone therapy and chemotherapy. It is the largest breast cancer treatment trial ever conducted, and the first precision medicine trial ever done, according to the authors.
“Half of all breast cancers are hormone receptor-positive, HER2-negative, and axillary node-negative,” said lead study author Dr. Joseph Sparano, at the Albert Einstein Cancer Center in New York. “Our study shows that chemotherapy may be avoided in about 70 percent of these women when its use is guided by the test, thus limiting chemotherapy to the 30 percent who we can predict will benefit from it”
Dr. Sparano added: “Before TAILORx, there was uncertainty about the best treatment for women with a mid-range score of 11-25 on the Oncotype DX Breast Recurrence Score test. The trial was designed to address this question, and provides a very definitive answer. Any woman with early-stage breast cancer 75 years or younger should have the test and discuss the results of TAILORx with her doctor to guide her decision regarding chemotherapy after surgery to prevent recurrence,” said
Based on evidence from several prior studies, the 21-gene expression assay is widely used to provide prognostic information about the risk of breast cancer recurrence within 10 years, and to predict which patients are most likely to derive a large benefit from chemotherapy. The test is performed on a tumor biopsy sample. Women with a low score (0-10) typically receive only hormone therapy and those with a high score (26-100) receive hormone therapy and chemotherapy.
Side effects of chemotherapy for breast cancer can be significant. Short-term side effects that occur during chemotherapy include nausea, vomiting, hair loss, fatigue, and infection, and, in younger women, early menopause or infertility. Neuropathy is another common side effect, with symptoms including numbness, tingling, or pain in the hands and feet, which may sometimes be permanent. Certain delayed side effects that may occur months or years after chemotherapy are rare, but potentially serious, including heart failure and leukemia.
The study found that for participants with gene test scores between 11 and 25 — especially among women aged 50 to 75 — there was no significant difference between the chemotherapy and no chemotherapy groups. Among women younger than 50, outcomes were similar when gene test scores were 15 or lower. Among younger women with scores 16 to 25, outcomes were slightly better in the chemotherapy group, the study reported.
At a median follow-up of 7.5 years, the study met its primary pre-specified endpoint indicating that hormone therapy alone was not less effective than chemotherapy plus hormone therapy in women with a Breast Recurrence Score of 11-25.
Nine-year rates were similar in the two treatment arms for disease-free survival (83.3% vs. 84.3%), distant recurrence (94.5% vs. 95.0%), and overall survival (93.9% vs. 93.8%), indicating no benefit from adding chemotherapy to hormone therapy.
Another important finding was identification of the group that did have some chemotherapy benefit – women 50 years or younger who had a Breast Recurrence Score of 16-25.
The researchers also found that women with a recurrence score of 10 or less had very low recurrence rates with hormone therapy alone, irrespective of age or other clinical factors. In addition, those with a recurrence score of 26 or higher had a distant recurrence rate of 13% despite chemotherapy and hormone therapy, indicating the need to develop more effective therapies for this group.
According to the authors, the findings suggest that chemotherapy may be spared in:
all women older than 50 years with hormone-receptor positive, HER2-negative, node-negative breast cancer and a Recurrence Score of 0 to 25 (about 85% of women with breast cancer in this age group)
all women 50 years or younger with hormone-receptor positive, HER2-negative, node-negative breast cancer and a Recurrence Score of 0 to 15 (about 40% of women with breast cancer in this age group)
This study received funding primarily from the National Cancer Institute, part of the National Institutes of Health. Additional support was provided by the Breast Cancer Research Foundation, Komen Foundation, and the U.S. Postal Service Breast Cancer Stamp.
Published Sunday in the New England Journal of Medicine.