Impact of clinical risk category on prognosis and prediction of chemotherapy benefit in early breast cancer (EBC) by age and the 21-gene recurrence score (RS) in TAILORx.

503Background: TAILORx established that endocrine therapy (ET) alone is non-inferior to adjuvant chemotherapy (CT) plus ET in EBC and a 21-gene RS of 11-25, with some benefit if ≤50 years (y) with ...