Initial findings from the Trial Assigning Individualized Options for Treatment, or TAILORx, show that, for women with early-stage hormone receptor-positive breast cancer that has a low risk of recurrence based on a test for the expression of 21 genes, 5-year recurrence rates are very low when postoperative treatment consists of hormone therapy alone.
New England Journal of Medicine, September 28, 2015 (See the journal article.)
Approximately 125,000 women in the United States were diagnosed with node-negative, estrogen receptor (ER)-positive breast cancer in 2014. Such women generally receive both hormone therapy and chemotherapy after surgery to remove their tumor. Although the use of adjuvant chemotherapy has contributed to lower breast cancer mortality rates overall, it is generally thought that most patients with node-negative, hormone receptor-positive breast cancer can be adequately treated with hormone therapy alone. However, the identification of which women could avoid chemotherapy has been difficult. A molecular test that assesses the expression of 21 genes associated with breast cancer recurrence, called the 21-gene recurrence score (Oncotype DX®), has been found to predict benefit from adjuvant chemotherapy in women with hormone receptor-positive disease. This study was carried out to provide prospective validation in a clinical trial of the test’s ability to predict which women can be safely spared from receiving adjuvant chemotherapy.
TAILORx was designed to determine whether a test that analyzes the expression of a group of genes that are associated with risk of recurrence among women with early-stage breast cancer could be used to assign patients to the most appropriate and effective treatment. The study, which began recruiting participants in 2006, has enrolled more than 10,000 women ages 18 to 75 at 1,000 sites in the United States, Australia, Canada, Ireland, New Zealand, and Peru, to various treatment options depending on their score on the 21-gene recurrence test. Women were eligible for the trial if they had been recently diagnosed with hormone receptor-positive, HER2-negative breast cancer that had not spread to the lymph nodes.
Women with the lowest 21-gene recurrence score (0 to 10), who constituted about 16 percent of the participants, were assigned to receive hormone therapy alone; women with a score of 11 to 25, who made up 68 percent of the participants, were randomly assigned to receive hormone therapy alone or hormone therapy plus adjuvant chemotherapy; and women with the highest scores (25 and higher) were assigned to receive hormone therapy plus adjuvant chemotherapy.
The ranges used to define risk in TAILORx are different from those traditionally used in other studies, where low risk is defined as a score of less than 18, intermediate risk is 18 to 30, and high risk is 31or higher. The thresholds used in TAILORx were chosen to minimize the potential for undertreatment of the subjects enrolled in the trial.
More than 1,600 women in the trial had tumors with a 21-gene recurrence score in the lowest range. These women received hormone therapy that consisted of an aromatase inhibitor (used in about 60 percent of patients), tamoxifen (used in one-third of the patients), tamoxifen followed by aromatase inhibitor therapy (used in 1 percent of the patients), treatments that suppressed ovarian function (used in 3 percent of the patients), or other or unknown treatments (used in 3 percent of the patients).
The trial, which was sponsored by NCI, was led by Joseph Sparano, M.D., of Montefiore Medical Center in New York and the ECOG-ACRIN Research Group. All of the adult cancer research groups of the NCI-sponsored National Clinical Trials Network (ECOG-ACRIN, the Alliance for Trials in Clinical Oncology, NCIC-Clinical Trials Group, NRG Oncology, and SWOG) participated in the trial.
Five years after study entry, in the low-risk subset that was the subject of this initial analysis, 93.8 percent of the women were free of invasive disease, 99.3 percent were free of distant relapse, and 98 percent were still alive. Recurrence events were, according to the authors, “far exceeded by second primary breast cancers, other second primary cancer events, and deaths from other causes.” These results provide support for the use of the 21-gene panel test to identify a low-risk subset of women that can be spared postsurgical chemotherapy.
Continued follow-up and analysis in the trial is ongoing, with full results expected in several years, to determine whether adjuvant chemotherapy improves outcomes over hormone therapy alone in women with higher recurrence scores.
Although this study clearly identifies patients who do not benefit from adjuvant chemotherapy, only 16 percent of those enrolled had a recurrence score of 10 or less. Nearly 70 percent of enrollees had a mid-range score of 11 to 25, and the results to date do not provide information about whether this subset of women can be spared chemotherapy.
“TAILORx is one of the first and most important trials using a gene panel test to determine how to most effectively treat women with breast cancer,” said Jo Anne Zujewski, M.D., of NCI’s Cancer Therapy Evaluation Program (CTEP). “These excellent results in the low-risk subset of women should help spare a significant number of women from being overtreated with chemotherapy. We eagerly await the results for all women in the study with the goal of only treating women for their specific type of breast cancer and sparing them the side effects of unnecessary treatments.”