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Updated: Feb 9, 2026

Optimization of a Multiplex RNA-based Expression Assay Using Breast Cancer Archival Material
Published on: August 1, 2018
Adjuvant Chemotherapy Guided by a 21-Gene Expression Assay in Breast Cancer
Joseph A Sparano1, Robert J Gray1, Della F Makower1
1From Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY (J.A.S., D.F.M.); Dana-Farber Cancer Institute, Boston (R.J.G.); Sunnybrook Research Institute, Toronto (K.I.P.), and McMaster University, Hamilton, ON (T.J.W.) - both in Canada; Loyola University Chicago Stritch School of Medicine, Maywood (K.S.A.), and Northwestern University, Chicago (L.I.W., V.G.K.) - both in Illinois; University of Michigan, Ann Arbor (D.F.H.); Virginia Commonwealth University School of Medicine and the Massey Cancer Center, Richmond (C.E.G.); University of North Carolina, Chapel Hill (E.C.D.), and Duke University Medical Center, Durham (J.A.O.) - both in North Carolina; Mayo Clinic, Jacksonville, FL (M.P.G.); National Institutes of Health, National Cancer Institute, Bethesda, MD (T.L., J.A.); Indiana University School of Medicine (S.S.B.) and Indiana University Hospital (G.W.S.), Indianapolis; Vince Lombardi Cancer Clinic, Two Rivers (T.J.S.), and Fox Valley Hematology and Oncology, Appleton (T.F.G.) - both in Wisconsin; Washington University, St. Louis (M.J.E.); National Surgical Adjuvant Breast and Bowel Project Pathology Office (S.P.) and University of Pittsburgh (A.M.B.), Pittsburgh; Emory University, Atlanta (W.C.W.); University of Texas, San Antonio (P.M.R.); Cancer Trials Ireland, Dublin (M.M.K.); Instituto Nacional de Enfermedades Neoplasicas, Lima, Peru (H.L.G.M.); Cancer Center of Kansas, Wichita (P.S.R.); Vanderbilt University, Nashville (I.A.M.); Rutgers Cancer Institute of New Jersey, New Brunswick (D.L.T.); and University of Hawaii Cancer Center, Honolulu (J.L.B.).
Background:
The recurrence score based on the 21-gene breast cancer assay predicts chemotherapy benefit if it is high and a low risk of recurrence in the absence of chemotherapy if it is low; however, there is uncertainty about the benefit of chemotherapy for most patients, who have a midrange score.
Methods:
We performed a prospective trial involving 10,273 women with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, axillary node-negative breast cancer. Of the 9719 eligible patients with follow-up information, 6711 (69%) had a midrange recurrence score of 11 to 25 and were randomly assigned to receive either chemoendocrine therapy or endocrine therapy alone. The trial was designed to show noninferiority of endocrine therapy alone for invasive disease-free survival (defined as freedom from invasive disease recurrence, second primary cancer, or death).
Results:
Endocrine therapy was noninferior to chemoendocrine therapy in the analysis of invasive disease-free survival (hazard ratio for invasive disease recurrence, second primary cancer, or death [endocrine vs. chemoendocrine therapy], 1.08; 95% confidence interval, 0.94 to 1.24; P=0.26). At 9 years, the two treatment groups had similar rates of invasive disease-free survival (83.3% in the endocrine-therapy group and 84.3% in the chemoendocrine-therapy group), freedom from disease recurrence at a distant site (94.5% and 95.0%) or at a distant or local-regional site (92.2% and 92.9%), and overall survival (93.9% and 93.8%). The chemotherapy benefit for invasive disease-free survival varied with the combination of recurrence score and age (P=0.004), with some benefit of chemotherapy found in women 50 years of age or younger with a recurrence score of 16 to 25.
Conclusions:
Adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone-receptor-positive, HER2-negative, axillary node-negative breast cancer who had a midrange 21-gene recurrence score, although some benefit of chemotherapy was found in some women 50 years of age or younger. (Funded by the National Cancer Institute and others; TAILORx ClinicalTrials.gov number, NCT00310180 .).
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