TAILORx (Trial Assigning IndividuaLized Options for Treatment Rx) randomized trial design. Oncotype DX is being tested in TAILORx, a prospective randomized phase III trial coordinated by the Breast Cancer Intergroup. The purposes of this trial are to confirm the prognostic value of the 21-gene recurrence score (RS), to determine the optimal management of patients with intermediate-RS, and to refine the utility of the assay in clinical practice. The accrual was recently completed and the first results will be disclosed in 2013. Patients with estrogen receptor (ER)-positive, node-negative breast cancers were eligible and were separated in three study groups according to their RS. High-RS patients (RS >25) received chemotherapy plus endocrine therapy, whereas low-RS patients (RS <11) were assigned to endocrine therapy alone. Patients with intermediate-RS (RS = 11 to 25) were randomly assigned to receive either hormonal therapy alone or hormonal therapy plus chemotherapy. To minimize potential under-treatment in both the high-risk and the randomly assigned groups, the RS ranges for TAILORx were different from those originally defined (11 to 25 instead of 18 to 31). FFPE, formalin-fixed paraffin-embedded; N0, lymph node-negative; RANDOM, randomization.