The majority of women with early-stage breast cancer and a mid-range score on a 21-tumor gene expression test see no added benefit from undergoing chemotherapy alongside hormone therapy during treatment, researchers reported this month at the American Society of Clinical Oncology’s annual meeting in Chicago, Illinois.
The researchers’ phase III trial—known colloquially as “TAILORx”—was funded primarily by the National Cancer Institute and “will transform care immediately, and for the better,” oncologist Harold Burnstein, MD, PhD, of the Dana-Farber Cancer Institute, said.
“These data provide critical reassurance to doctors and patients that they can use genomic information to make better treatment decisions in women with early stage breast cancer,” Burnstein said in an ASCO release. “Practically speaking, this means that thousands of women will be able to avoid chemotherapy, with all of its side effects, while still achieving excellent long-term outcomes.”
And though most breast cancer patients aren’t hit with long-term side effects of chemo, like heart failure or leukemia, nausea, vomiting, neuropathy, hair loss, fatigue and infection are all common consequences of the treatment. In younger women, early menopause and infertility are possibilities.
TAILORx, as the largest breast cancer treatment trial ever conducted, enrolled 10,273 women with hormone receptor-positive, HER2-negative, axillary node-negative breast cancer, first study author Joseph A. Sparano, MD, and colleagues wrote in the New England Journal of Medicine, where results were published June 3. That type of cancer accounts for around half of all breast cancers diagnosed worldwide.
The women’s conditions were assessed using the Oncotype DX Breast Recurrence Score, a 21-gene expression assay used often in clinical practice to gauge the risk of cancer recurrence within 10 years, Sparano, the associate director for clinical research at the Albert Einstein Cancer Center and Montefiore Health System in New York, said.
The system generates a risk score between 0 and 100. Women whose scores fall between 0 and 10 are often referred solely for hormone therapy after surgery, the authors explained, while women who fall within the 26-100 range typically receive both hormone therapy and chemotherapy. And that’s been a helpful guide, Sparano said—but it leaves a critical group of women unaccounted for.
“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,” he said.
Of the women Sparano et al. studied, 6,711—or 65 percent of the total pool—recorded a mid-range score of 11-25. Those patients were randomized to either receive hormone therapy alone or hormone therapy supplemented with chemo.
After an average seven and a half years of follow-up, the researchers said they met their met their primary endpoint indicating that hormone therapy alone wasn’t less effective than chemotherapy plus hormone therapy in women with a Breast Recurrence Score of 11-25. Disease-free and overall survival rates were similarly high in both cohorts.
Sparano and colleagues said their results suggest chemotherapy can be spared in two major patient groups: women older than 50 with hormone-receptor positive, HER2-negative, node-negative breast cancer and a recurrence score between 0 and 25, and women younger than 50 with the same type of cancer and a recurrence score between 0 and 15. The researchers also found that women younger than age 50 with a recurrence score of 16-25 could benefit from some chemotherapy.
“TAILORx provides the most definitive answer about how to treat women with Oncotype DX Recurrence Scores of 11 to 25, as well as 0 to 10,” Sparano said in a release from Genomic Health, Inc., which developed the risk assessment test. “The results provide an unprecedented level of precision and the highest level of evidence supporting the use of this test to guide adjuvant chemotherapy use in this population, which accounts for about one-half of all breast cancers.”