Chemotherapy found to provide no benefit to nearly three quarters of women with the most common type of breast cancer.

Chemotherapy has been a common component of treatment regimens for women found to have early-stage breast cancer. Results of a recent study – the Trial Assigning Individualized Options for Treatment (Rx), or TAILORx, raises doubts about this practice, however. 

The TAILORx study was a large-scale, phase 3 clinical trial specifically designed to investigate possible approaches to providing personalized cancer treatment. It opened in 2006 and enrolled 10,273 women with the most common form of breast cancer - hormone receptor (HR)-positive, HER2-negative, axillary lymph node-negative breast cancer - at 1,182 sites in the United States, Australia, Canada, Ireland, New Zealand, and Peru.

The study was funded by the Breast Cancer Research Foundation, Komen Foundation, and the Breast Cancer Research Stamp, which was initially authorized by Congress in 1998 and has since raised more than $86 million for the funding of breast cancer research. 

The tumors of women enrolled in the study were analyzed using the Oncotype DX Breast Recurrence Score test from Genomic Health, a 21-gene expression test. Each was assigned a score from 0-100 for their risk of cancer recurrence. Those patients with a low risk (0-10) received hormone therapy, those with a high risk (26 and above) received hormone therapy combined with chemotherapy, and those with an intermediate score (11-25) randomly received hormone therapy alone of the combination of hormone and chemotherapy. 

The key finding from the study was that treatment with chemotherapy and hormone therapy after surgery is not more beneficial than treatment with hormone therapy alone. Specifically, the proportion of women who had not died or developed a recurrence or a second primary cancer was similar whether or not chemotherapy was included in their treatment regimen. The rates of overall survival were also similar.

Based on the results, chemotherapy may be avoided for women of any age with a recurrence score of 0-10, women older than 50 with a recurrence score of 11-25 and women 50 years and younger with a recurrence score of 11-15 - a total of approximately 70% of patients diagnosed with early-stage breast cancer.

Chemotherapy is recommended for the remaining 30% that either have a high recurrence score (26 or above or are 50 or younger with a recurrence score of 16-25. 

"The new results from TAILORx give clinicians high-quality data to inform personalized treatment recommendations for women," said lead author Joseph A. Sparano, M.D., associate director for clinical research at the Albert Einstein Cancer Center and Montefiore Health System in New York City and vice chair of the ECOG-ACRIN Cancer Research Group. "These data confirm that using a 21-gene expression test to assess the risk of cancer recurrence can spare women unnecessary treatment if the test indicates that chemotherapy is not likely to provide benefit."