Results from the Phase III TAILORx clinical trial have indicated that most women with hormone receptor-positive, HER2-negative, axillary node-negative early-stage breast cancer and a midrange score on a 21-tumor gene expression assay do not need chemotherapy after surgery.
Experts suggest that these findings, presented at the Annual Meeting of the American Society of Clinical Oncology (ASCO; 1–5 June 2018, IL, USA), could have an immediate impact on clinical practice, sparing thousands of women the side effects of chemotherapy.
According to the authors, TAILORx is the largest breast cancer treatment trial to date, and the first precision medicine trial. Lead author Joseph Sparano (Albert Einstein Cancer Center and Montefiore Health System, NY, USA) commented: “Half of all breast cancers are hormone receptor-positive, HER2-negative, and axillary node-negative. Our study shows that chemotherapy may be avoided in about 70% of these women when its use is guided by the test, thus limiting chemotherapy to the 30% who we can predict will benefit from it.”
“Before TAILORx, there was uncertainty about the best treatment for women with a midrange 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.”
The TAILORx trial enrolled 10,273 women with hormone receptor-positive, HER2-negative, axillary node-negative breast cancer; the most common type of breast cancer. Of those, 6711 had a midrange recurrence score of 11–25 and were randomly assigned receive either a combination of hormone therapy and chemotherapy, or hormone therapy alone.
Followed up at a median of 7.5 years, the study met its primary endpoint of disease-free survival, indicating that hormone therapy alone was not less effective than hormone therapy plus chemotherapy 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. However, researchers did find that women of 50 years or younger who had a Breast Recurrence Score of 16–25 benefited from chemotherapy.
In addition, the team observed 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. Plus, 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.
The authors concluded that chemotherapy can be spared in:
All women older than 50 years of age with hormone-receptor positive, HER2-negative, node-negative breast cancer and a Recurrence Score of 0 to 25 (approx. 85% of women with breast cancer in this age group)
All women 50 years of age 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)