ESR1 and breast cancer: PFKFB4 had an hazard ratio (HR) of 7.38 (95% CI 1.69–32.3; p = 0.008) in univariate Cox analysis and retained prognostic power (HR 7.44, 95% CI 1.67–33.2; p = 0.009) when adjusted by tumor size, lymph node status, grade, estrogen receptor status, human epidermal growth factor receptor 2 status and subtype, which indicated PFKFB4 was an independent prognostic factor in breast cancer.