ESR1 and neoplasm: After adjustment for age, ER, PR and HER2 status, grade and/or tumor size, multivariable Cox analysis demonstrated that the 3q gene signature remained an independent prognostic marker for DMFS in GSE11121 (HR 1.83, 95% CI 1.41–2.37, P = 6.45e-06) and GSE2034 (HR 1.38, 95% CI 1.11–1.72, P = 0.004, Supplemental Table 4), respectively.